Could the Hulk show up here? I don't rule this possibility out. Sure Steven Strange will take the stage and most of the focus will be on him.
But he's not an isolated character within the Marvel Universe. Some connections will have to be established at some point. And the question is: why not now?
Introducing the Hulk in Doctor Strange is plausible: Bruce Banner wants to control the Hulk. Science has failed him so far. Could magic help?
Turning to Doctor Steven Strange to cure "“ or help contain "“ his condition is a plot scheme Marvel could easily employ. What do you think guys? It makes sense to me!
Guardians of the Galaxy 2

Yeah, well, before the release of Age of Ultron, rumor had it the Hulk will leave the planet and thus allowing the studio to connect the terrestrial slice of the MCU to its stellar dimensions.
This seemed like the ideal opportunity to connect the Avengers with the Guardians of the Galaxy. And the Hulk "“ what a strong link! But unfortunately the Quinjet didn't leave the atmosphere.
How is Guardians of the Galaxy 2 a possibility for the Hulk then?
