According to industry insider Daniel Richtman, there is a very small chance that Doctor Strange 3 will be released between Avengers: Doomsday and Avengers: Secret Wars, which are

Avengers: Doomsday is still more than a year away, but it’s not too early to learn a few of the movie’s secrets. For instance, Doctor Strange won’t be appearing in this next Avengers film, apparently.

Benedict Cumberbatch gives NSFW response to question about Doctor Strange being in Avengers: Doomsday. Those who were excited to see Benedict Cumberbatch's Doctor Strange in Avengers: Doomsday will be disappointed with the latest update on his status. However, there is light at the end of the tunnel.