It would actually make perfect sense for Disney to open Avengers 2 and Ep7 at opposite ends of May. Last year, the big memorial day movie was Men in Black III. It'd been three weeks since The Avengers opened and it was the movie to finally knock it from the #1 spot at the weekend box office.

If Disney opens Star Wars on memorial day weekend (as damn well they should) and assuming Avengers 2 is once again the #1 movie for the three weekends preceding, they could end up enjoying six or seven weeks as king of the box office.

Oh, and on the whole "how will it be shot" debate, I think it's quite likely Abrams will shoot this thing in 2D. All four of his other movies were shot on film, in cinemascope, just as the OT was. Perhaps the "on film" part might change (they could go with Arri Alexa 4:3 cameras), although I'd think JJ would prefer actual film if it's still available next year. Disney will in all likelihood convert it to 3D to squeeze an extra hundred million out of the box office.

I don't see Hollywood's obsession with 3D blowing over anytime soon. If the vast majority of the movie-going public don't know whether or not the movie they're seeing was shot in 3D, the studios are just gonna keep on exploiting that ignorance. Even I have to admit the conversion tech has come a long way. My pre-screening of Man of Steel ended up being the 3D version (projected in real-d) and I found everything quite natural-looking. The only real drawback was the darkening caused by the polarizing filters. Also, while I didn't go see the full movie this way, the converted opening scene of JJ's own Star Trek Into Darkness (shown in front of Imax 3D screenings of The Hobbit) looked pretty natural as well.

Also, it's important to note that while converted 2D footage will never be as convincing as the actual native material, more and more of these tentpole releases are having their cgi rendered in stereo. So, there's at least something "truly" 3D that people are getting out of these converted movies.