The whole TDKR shifting AR kerfuffle got me to thinking about AR and brought to my mind a question: why don't more directors use open matte? That way, you can use 2.4:1 for theatrical release and have an OPTION of 16:9 for bluray. Of course if a director insists his movie needs to be seen in widescreen everywhere, that's fine, but why don't more directors think of how the movie will be most often seen -- on a HDTV or mobile device, which increasingly means 16:9. My guess is if you give viewers an option, most will choose the 16:9 one, because most people have a non giant TV and don't give a rat ass about directorial vision. With open matte, you are not cropping and pan and scanning. If it was good enough for Kubrick, I think it's good enough for Michael Bay.
Now, if you're doing a lot of cgi, obviously you will be cropping a good chunk of your money off the screen for your theatrical release, but your audience will get it back on bluray. The other problem is distribution. Probably too much expense to do separate releases. You don't want to bit squeeze two versions on same disc. I think you can come up with some clever encoding scheme around this, or just have the 16:9 version and let the player mask off the top and bottom for the cinephiles.
Ps: I think skyfall was shot open matte for (pseudo) IMAX and cropped to 2.39:1 for regular theaters. Will it be cropped to 16:9 or 2.39:1 for the bluray?