In just two years, over-the-top TV has gone from niche endeavor to mainstream preoccupation. CBS launched its All Access service at the end of 2014, followed by Dish's unveiling of Sling TV at CES 2015 and HBO's announcement of HBO Now a few months later. Then came Showtime's streaming service, a national launch for Playstation Vue and much, much more.

This past year brought two major telecom companies into the fray. Verizon Communications Inc. (NYSE: VZ) entered its first full year with Go90 on the books (the mobile service officially launched in late 2015), and AT&T Inc. (NYSE: T) kicked off DirecTV Now. Meanwhile, several online stalwarts are promising new content offerings for 2017, including Facebook , Hulu LLC and YouTube Inc.

Here are some of the top highlights from 2016, along with a look ahead and even one genuine big-deal prediction for next year.

The good and bad for Sling TV
Sling TV has grown quite a bit since launch, adding to its channel line-up and expanding its bundle options. The good news is that Dish Network LLC (Nasdaq: DISH) has attracted more than 600,000 estimated subscribers to the Sling TV $20-per-month OTT service. The bad news is that Dish is losing pay-TV customers overall (116,000 in the third quarter), meaning that even with Sling TV gains, the satellite TV company is not only dropping subscribers, but also significantly eroding its average revenue per user. (See Dish Bleeds More Subs, Faces OTT Rival.)

Here's the conundrum. Sling TV offers one of the best content bundles for a price point well under the standard cable TV package. If it increases the price, it will be hard to sustain its growth. But if it doesn't increase the price, Dish may have a hard time reconciling the bottom line.

One potential way to attract new customers and new money is to introduce new features. Dish is currently beta-testing a cloud DVR service to go with Sling TV that could bring in additional revenue. It also appears to be on the verge of coordinating the launch of AirTV to combine the Sling TV service with over-the-air content and other OTT apps on an Android-powered device. If successful, the AirTV player could help boost Sling TV's subscriber growth. (See AirTV Promises Best of OTA & OTT.)

Where has Go90 gone?
Few video services have gotten as much attention before launch as Go90, but for all the marketing effort, Verizon so far has little to show on the subscriber front. Or more accurately, Verizon has nothing at all to show because it hasn't released any subscriber totals. The signs aren't positive, however. While Verizon keeps throwing money at the service, CEO Lowell McAdam has tried to walk back expectations, acknowledging that Go90 may have been "a little bit overhyped." (See Verizon Backpedals on Go90.)

That said, Verizon is still very much in building mode with Go90, acquiring and testing out content that it believes will resonate with younger audiences and continuing to invest in its advertising platforms. Importantly, Go90 is not meant to be a cable TV replacement. First of all, it's free. And second of all, the video library is tuned more in the direction of web-born video than traditional television.

One of the big things that Go90 has going for it is that any video streamed from the service is exempt from Verizon's mobile data usage caps. That's a big incentive for potential viewers because it means they don't have to worry about additional fees while using Go90. And the longer users spend with the service, the more ad revenue Verizon stands to gain.

The FCC had signaled it would take a closer look at this zero-rating practice to determine if it represents anti-competitive behavior. However, now that the FCC is shifting into Republican hands, the concern that regulators might block zero rating is almost certainly moot. (See AT&T & Trump Tangle Net Neutrality's Web.)

Next: DirecTV Now disappoints

DirecTV Now disappoints
DirecTV Now is AT&T's take on OTT video, and it's much more like traditional television than Verizon's Go90. The service comes with major broadcast channels (minus CBS) and cable networks bundled in different ways, depending on how much a customer wants to pay. That channel lineup however, was one of the first disappointments at launch. While AT&T CEO Randall Stephenson had promised that AT&T would make 100 channels available for $35 per month, it turns out that $35 is only a promotional price for the "Go Big" bundle. Normally, the 100-channel lineup will cost $60 per month, with only around 60 channels available for the initial $35 fee. (See Why DirecTV Now May Flop and AT&T Debuts DirecTV Now on New Video Platform.)

Another big disappointment is that local network channels aren't available through DirecTV Now in every market. Access is difficult to earn because it requires making agreements with every local affiliate station, but for viewers in markets where those locally owned affiliates dominate, the issue is a potential deal-breaker.

And finally, perhaps the biggest disappointment with DirecTV Now is that it has suffered multiple outages. Phillip Swann has reported extensively on the service disruptions, which suggest that AT&T's platform for DirecTV Now wasn't really ready to scale at launch.

Want to know more about video and TV market trends? Check out our dedicated video services content channel here on Light Reading.

Like Verizon, AT&T is playing a long game when it comes to OTT video, and if DirecTV Now has only marginal success in its early days, that may help the company keep more customers tuned to its legacy DirecTV service with the higher margins that entails. In the long term, the big issue for AT&T is consolidating its video platforms so that the telco can make the most of its customer data and advertising opportunities. DirecTV Now is one step in that direction, providing the platform that AT&T says all of its TV services will migrate to over time. Bottom line, AT&T may not need or even want DirecTV Now to be a commercial success early on as long as it can use the platform and learnings from the service to position itself for a future all-IP video world.

Download-to-go gets big
OTT video is all about streaming, but as Amazon.com Inc. (Nasdaq: AMZN) has shown, customers still have an appetite for offline TV access. Amazon started offering a download-to-go option for some of its Prime TV content in late 2015, and the feature proved popular enough to sway Netflix Inc. (Nasdaq: NFLX) to do the same a year later. The content available for downloading is still limited, but the option applies to some big-name titles, which means many subscribers will be able to find something to watch if they want to cache an Amazon or Netflix show away for offline viewing. (See Netflix Queues Up Video Downloads.)

What's interesting about the download-to-go feature is that it's part of a larger trend toward hybrid services that take advantage of both local and cloud resources. Sometimes it makes sense to store and process content locally, and sometimes it makes sense to stream it from the cloud. More services -- both consumer and enterprise -- are starting to make use of both options. (See Small Arctic ISP Caches Netflix in New Way and Technicolor Brings AWS Home to Gateways.)

What's ahead
For all the big things that happened with OTT video in 2016, the market promises to be even more active in 2017. Hulu, which launched a commercial-free version of its service in July, is now planning to unveil a live TV streaming option early next year and already has licensing deals in place with Fox Broadcasting Co. and Walt Disney Co. (NYSE: DIS), among others. (See Hulu Signs Fox, Disney for New OTT Offering.)

YouTube also has a new OTT service planned for early 2017. In a counterpoint to Hulu, YouTube has reportedly signed up CBS Corp. (NYSE: CBS) for the Unplugged launch, while apparently also negotiating seriously with Fox and Disney. (See YouTube Lands CBS for Unplugged – Report.)

CBS itself has big plans for its existing CBS All Access service. With more than a million subscribers already, the OTT streaming service will add new original content next year, including a spinoff of The Good Wife and a new Star Trek series.

And then there's Facebook. Variety reported recently that the social media company is working to bring exclusive content to its platform in the future, including scripted and unscripted shows. Facebook isn't looking to create a cable TV replacement, at least not yet, but the company is clear that it wants to be a major player in online video, and ultimately that may mean a bigger entry into the television market.

A prediction for 2017
There's a lot we don't know yet about 2017, but in addition to OTT news that's already been announced, I'm willing to venture at least one prediction about a company that's been relatively quiet on the OTT front. I'm betting that Comcast Corp. (Nasdaq: CMCSA, CMCSK), despite assurances that it has no need to go over the top, will advance its IP-based Xfinity on Campus product beyond collegiate grounds. In theory, Comcast's Stream product is the company's answer to OTT video demand, but Stream's skinny bundle is still only available in a few markets, and certain information I've heard suggests there's something new on the way; something new that will more closely resemble the bigger-bundle Xfinity on Campus service.

Comcast will always argue that its IP-based video products aren't OTT services because they operate over a managed network. But for consumers, the experience is much the same. It looks to users like content is coming over the Internet, and that content is available on Internet-connected devices.

I wouldn't take my Comcast prediction to the bank yet, but I'd give it more than even odds for 2017. And post-2017, I expect we'll even see Comcast go outside its footprint with IPTV services. After all, if AT&T, Verizon and a host of OTT companies are reaching out to a national audience, it would be silly for Comcast not to do the same.

— Mari Silbey, Senior Editor, Cable/Video, Light Reading