This whole rumor only started because Brendan McCarthy vaguely mentioned having a conversation with someone at Disney about PIXAR animating a Doctor Strange movie.
A) It could have been just that, a conversation
B) They may have meant the CGI element of the film
Either way, people officially in the know have since shot that down because PIXAR is strictly developing their own properties for animated films. Would be cool to get Brad Bird back to Disney on a Fantastic Four movie, though.