Perhaps following in the footsteps of Guardians of the Galaxy, it's being stated that the Doctor Strange movie will not be an origin story, which may mean fans may never get to see how Stephen Strange aquires his powers or becomes Sorceror Supreme.
It is possible that a short snippet of footage might be shown, similar to what Marvel and James Gunn did for Star-Lord in Guardians of the Galaxy, but it's possible that Marvel might just have the character as "Doctor Strange" and already having powers, which would eliminate the need of having to explain everything.
The following video features various people from film websites where one says he has a "scoop" that the previous Doctor Strange draft has been set aside, and that an all-new story is being developed featuring no origin.
"Marvel's new thing is no more origin stories. So the Doctor Strange movie no longer has an origin. It begins in media res (the midst of things). It has Doctor Strange already as Sorcerer Supreme. And it's a totally new script. John Spaihts is working totally new on his own without the previous stuff. They are not even touching the previous stuff."
Skip to the 52-minute mark to here the blurb: