Apple's (AAPL -0.57%) CEO Tim Cook has promised to release several new products this year. Based on recent reports, one of those products is an improved version of the Apple TV set-top box.

The next Apple TV could be sold as a replacement to the traditional cable box, offering cable subscribers an improved viewing experience. Bloomberg reports that Apple was working on a deal with Time Warner Cable (NYSE: TWC), aiming to offer its subscribers the improved Apple TV later this year.

Now that might not happen. On Thursday, Comcast (CMCSA 1.62%) announced that it was purchasing Time Warner Cable, throwing the deal with Apple into doubt. While it could still happen, there are a number of reasons why Comcast might not be willing to work with Apple.

Comcast has invested heavily in its own set-top box
For starters, Comcast -- unlike Time Warner Cable -- has invested heavily in its own set-top box technology. Gone are the days of sluggish, buggy cable boxes: the new X1 and X2 platforms offer Comcast subscribers a highly advanced, cloud-based set-top box complete with voice commands and personalized recommendations.

Any device from Apple would compete with directly with Comcast's new platform, and that's an obvious problem. Not only do Comcast's X1 and X2 differentiate it from its satellite-based competition, but they also serve as gateways to Comcast's pay-per-view services.

Comcast's Xfinity On Demand store competes directly with Apple's iTunes, offering Comcast subscribers the ability to purchase and rent digital movies. Replacing Comcast's platform with Apple's boxes would give iTunes all of Comcast's On Demand business.

But Comcast has worked with Microsoft
That said, Comcast has been willing to work with Microsoft (MSFT -1.84%) in the past. The Xfinity TV app, for example, allows Xbox 360 owners to replace their Comcast cable box with Microsoft's video game console, burying Comcast's interface behind Microsoft's technology.

The same is true for the Xbox One, although it should be noted that the full Xfinity App is still unavailable. That might just be a temporary delay given that the Xbox One has been on the market less than three months, but it could be something more.

Apple's TV revolution could be delayed yet again
The first Apple TV hit the market in 2007, but Apple's management has famously characterized it as "a hobby." The real Apple TV product has been anticipated for years, and it was finally starting to look like 2014 would be the year of its release.

Comcast's purchase of Time Warner Cable, however, complicates matters significantly. While Comcast has been willing to work with Microsoft in the past, its recent push into more advanced set-top boxes suggests that it might not be as willing to work with Apple as Time Warner Cable had been.

The deal will take some time to close, and regulators could reject it. Moreover, given Comcast's massive footprint, Apple would've had to work with them at some point anyway. Still, the deal complicates matters -- an Apple cable box alternative in 2014 is now far from a foregone conclusion.