I know the show was cancelled, but I do think if there was a third season, Wally would return.
- His death wasn't really heroic like his (near) death in Justice League Unlimited against Luthor-Brainiac was.
Wally, Barry and Bart did all the same thing. But Wally simply botched. He was slower than the rest of them. That's the sole reason why Wally died and the others didn't.
A way more noble death would be Barry and Bart getting knocked out by (non-lethal) beams (and Jay Garrick too - by the way, where was Jay Garrick (The Original Flash)? He was probably faster than Wally and could have filled his role) and then Wally being the only one left and compensating the absence of the others by running faster than the light speed, thus sacrificing his life while saving the world.
The way Greg Weisman killed off Wally, I think that beam just transported Wally to another place. And this would have been explored in the Third Season. Unfortunately, the show was cancelled, so Greg will never have the chance to bring Wally back.