This has been rumored for months.
There's still one issue left and it appears that people from New Earth are going to make their way to (I'm assuming) Earth 1. This leads me to believe we'll see Bruce again real soon.
What happened to Batman was (if I remember right) what happened to Sonny Sumo. Sonny was also blasted by the Omega Beams and was scattered in time (I think). This is probably how Bats will end up on Earth 1 (I don't know. I'm just speculating here.)
As far as the decision to off him so soon after TDK?
Why not do it now with so much interest going on? I think Batman is the only major DC character who's never "died". They've already started the hype on The Battle for the Cowl storyline to see who takes up the mantle next and I can see them having Bruce back just in time for...the next Batman movie.
But I'm just guessing.