Interview Magazine has a featured article where to two actors interview each other. The Marvel movies are discussed where Benedict Cumberbatch mentions he's part of Tom Hiddleston's crew, which may mean Thor: Ragnarok.
HIDDLESTON: How did you feel about joining the Marvel universe?
CUMBERBATCH: I felt it was all about the part rather than everything else. I've been to Comic-Con, and it's a very nice way to give back to the fans that drive these things. It was quite scary. I felt like Pink Floyd. It's just like, "Hello, hi," after the fans are all screaming. That side of it is just phenomenal, and it makes me giggle, and I don't know whether I'll get used to that. I can't wait to see how it expands the universe. I'm also part of your crew! It's an amazing cast of actors. And it's the most fun hard work you'll ever do, I think, as an actor. They really know how to treat you right. And the material is challenging, witty, and a lot of fun to do. Doctor Strange is a complex, funny, but exciting character.
Interestingly enough, back in July saw Benedict Cumberbatch tease an appearance with Tom Hiddleston in a Marvel movie as well.
It's possible with DC having the Justice League movie coming out two weeks after Marvel's Thor 3 that they could be adding additional characters to the cast. Thor: Ragnarok could potentially be a second Avengers-lite movie following Captain America: Civil War.
Doctor Strange opens November 4th.
"Thor: Raganarok" has a November 3, 2017 release directed by Taika Waititi starring Chris Hemsworth as Thor, Mark Ruffalo as Hulk/Banner, Tom Hiddleston as Loki, Idris Elba as Heimdall, Cate Blanchett as Hela, Tessa Thompson as Valkyrie, Jeff Goldblum as Grandmaster, Anthony Hopkins as Odin and Sam Neill in an unknown role.