The next Avengers movie is a good ways off but the script is already being worked on. Mark Ruffalo had the following tweet recently:
“I got a text from Joss Whedon the other day. Sounds like he is writing some very interesting stuff for Banner and his alter ego The Hulk.”
Not a lot of news but at least it seems like Joss is going to not just use the Hulk as a big monster but actually give some screen time to Bruce with some good story line.