I am of the mind set that someone will end up dead at the conclusion of the Final Crisis series. That's just the way it is with these big crossover events nowadays... With that being said, I have no idea as to who the sacrificial hero is going to be. My first impulse is to say that it's going to be Wally(Flash)West, but lately, I've been hearing other names thrown around, such as Wonder Woman(nah) and Batman...
The Batman possibility seems the most interesting due to the fact that according to Crisis/Batman writer, Grant Morrison, the events of Batman R.I.P. conclude in Final Crisis. That is kind of intriguing due to the fact that I could easily see Batman dying to end Final Crisis, and in the Bat comics, there would then be a fight over who the new Batman should be.
Seeing as that pretty much all the Bat allies are getting their series cancelled(Nightwing, Robin, Birds of Prey), to me it would make the most sense for Nightwing to take up the mantle of Batman. To go even further, Robin could take over the Nightwing costume, which would start up a new Nightwing series staring Tim Drake, while Damian Wayne could begin to train with Dick Grayson to become the next Robin.
Honestly, everything I just wrote seems way too far fetched, but who knows? Still, to be honest, if someone was to drop dead to end Final Crisis, I still think it's going to be Wally, thanks mainly due to the return of Barry Allen. But that's just what I think. The question here is does anybody else have any opinion on this topic? I'd be curious to hear some other opinions.