I think at this point, Overwatch has earned its shot at a movie.
Blizzard has created short after emotional short for the universe, whether it's to promote an upcoming new character or just do a bit of worldbuilding -- and the comparisons to Pixar are usually flying left and right. I mean, it didn't work out so well for the Warcraft movie when Blizzard moved into that arena, but it would be a shame if they just gave up. Especially since Skylanders is about to debut its third season on Netflix, proving some degree of success.
Speaking of the Skylanders IP holder, Activision pushing Blizzard to do it is another reason why it might happen. Speaking to MCV, Activision Consumer Products Group head Tim Kilpin (who used to do franchise management at Disney), says that an Overwatch movie project is something that the company "would like very much" to go ahead on.
Expanding a bit, Kilpin states, "We’re a platform and a portfolio, these franchises exist across multiple platforms. It’s not just the game as a driver, but it’s linear content [movies and TV] as a way to expand the audience and expand the opportunity and then esports [too]. Pull all that together and you’re talking about franchises that are frankly like no other."
I mean yeah, it could work. Just keep it simple, Overwatch versus Talon, or the Rise of the Omnics storyline, and it would be a pretty marketable concept. Maybe one that people have seen before (superhero film or sci-fi dystopia respectively), but marketable nonetheless.