Not all 3D movies always have 3D trailers. It is quite possible that there will be a 2D version of the trailer (to be shown in 2d theaters).
I mean, there will be TV commercials in 2D (maybe even a big one during the Superbowl, like last time), so why not a trailer in 2D?
...And, yes. Abrams said he would have preferred the movie to be in 2D, but Paramount overruled him.
The teaser trailer to this movie will be first shown in 3D, its too big a movie for the studio to do otherwise. What's coming out in the next 8 weeks or so, in 3D, that Paramount can use?
There will be a trailer attached.