We've already established that the Thor franchise is sort of Marvel's redheaded stepchild. So how do they fix that with the third film? For one, they brought in Taika Waititi to direct it, a bold and exciting choice. For another, they've decided to give Thor: Ragnarok the central plot position that Captain America: The Winter Soldier had - the MCU will feel the implications of this movie. And third, if JoBlo is right, they're bringing in the big guns. The big green guns. The Hulk.
According to the site Hulk will co-star in Thor: Ragnarok, and he will show up on a planet that is neither Earth or Asgard. As you recall from the end of Avengers: Age of Ultron, Hulk was in a cloaked Quinjet going who knows where, but cruising very high in the sky. Could Hulk have somehow found his way off the planet?
Bringing in Hulk makes all the sense in the world. He's a character who is popular but who cannot have his own film, thanks to a deal with Universal. Putting him in Thor: Ragnarok ties that film deeper into the Marvel Cinematic Universe and raises audience interest in a big way. Also, I think Hulk works best on screen as a supporting player, at least until such time as Marvel gets the cojones to do a Mr. Fixit type story with him - ie, something other than 'They're chasing me and I change into a monster!,' which has been done enough.
Could this be true? Sure! I buy it. I'm getting very curious about Ragnarok, and I hope that it lives up to its status as the lynchpin of Phase Three.