A very reliable source is saying that Depp has already taken a meeting with the studio, and apparently the actor is very interested in pursuing it. It’s not really a huge surprise that this could be happening, after all Depp already has a very tight relationship with Marvel’s owners… Disney. He tends to make the studio tons of money… when the movie is good. Unfortunately The Lone Ranger didn’t live up to anyone’s expectations. He’s also a long time fan of Strange as well, which doesn’t hurt the situation.
Depp is currently signed on to do a fifth Pirates of the Caribbean movie, but if he ends up taking Dr. Strange that studio would shift around the production schedule for it so he could do both. This means that they are looking to start production on the comic adaptation fairly soon.
As you know, Marvel movie deals with actors are insane, so it will be interesting to see if they are able to work out a deal with Depp. The script that has been written will have to go through an overhaul, especially since the current script centers on a 30-year-old Strange, and Depp is 50. I don’t think Marvel or Disney will have any problems making the changes they need to make if they actually get Depp officially on board.
Dr. Strange is going to be part of Marvel’s phase three plan, and will most likely be released sometime in 2016. You never know when or where the character will show up though! There’s always a chance we’ll see the character show up in a post-credits sequence of Avenger: Age of Ultron.