Warning there will be spoilers here for Doctor Strange:
The Infinity Stones
As has been speculated for some time, The Eye of Agamoto houses the Time Stone. That means there is one Infinity Stone left unaccounted for. This also means there are two Infinity Stones on Earth. We all know Thanos is finally deciding to get out of his chair and do it himself. So a visit to the Doctor Strange and his mystic comrades is expected.
In a post credits scene that is more than likely a shortened scene from Thor: Ragnar ok, we see Thor has gone to Strange for help in locating his father. How exactly Thor learns of him is unknown at this point. But we do see that Strange knows more about Thor and specifically that Loki is on Earth. Loki is a threat to Earth and Strange is having none of that. The condition is that Strange will help Thor locate Odin on the condition that the Asgardians stay away from Earth.
There seemed to be some tension between Strange and Thor. Probably due to the fact that Loki is on Earth. We all know Thor has a blindspot towards his brother. Plus most of the Earth’s biggest problems stem from the Asgardians in various ways. Probably shouldn’t expect Strange’s role in Thor: Ragnarok to be more than a significant cameo.
Avengers: Infinity War
Doctor Strange and Wong have been confirmed to appear in the movie and presumably the fourth Avengers movie that will be sshooting simultaneously. Strange plays the unconnected third party to the splintered Avengers. He may also bring knowledge about Thanos who is a compete unknown to Earth’s Mightiest Heroes. Will he be the one to unite the fractured heroes? As we saw in the movie, Strange was willing to risk an eternity of infinite deaths to save Earth whereas in the beginning he is only interested in taking medical cases that wouldn’t harm his reputation. He is probably the best example of someone getting out of their own way. The other heroes can learn something from him.