Comics are a visual medium, of course, but movies are even more so, with their huge Techncolor images up on that huge screen.
So visuals are extremely important. And a cape adds a lot to a character's visual grandeur and importance. Dr. Strange should have his cloak of levitation as soon in the movie as is reasonable, to help establish his importance and power.
It would likely be a combination of practical effects capes and CGI capes, just the same as they've done for Thor and other superhero characters with capes.
A long cape can move on screen in a way that robes just cannot.
Maybe I'm too much of a purist, but not only do I really hope they keep Dr. Strange's long cape in the movie, but I hope it even has the high, stand up collar, and iconic Steve Ditko horns.
The high collar may not make it, since from some camera angles it would block, or even just partially block, the actor's face.
We see Cap without his helmet a lot, and we get that "inside view" of Tony Stark when he's wearing the Iron Man armor. Both are so we can better see the actor . . .acting.
So while I'm not expecting it, I would love the see the Ditko design survive into the movie.