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

While Marvel has not officially announced Doctor Strange 3, it sounds like the studio is developing the sequel behind-the-scenes, collaborating very closely with star Benedict Cumberbatch. In an interview with Variety,

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.