I haven't been able to keep up with Blackest Night quite as much as I'd like to, particularly the tie-in miniseries. Even so, I have some thoughts about where the series might be going. I'm still pretty well convinced that the story's going to end with Hal Jordan becoming the (temporary) White Lantern, uniting the emotional spectrum with the power of life. The effect of this, I imagine, will be the undoing of a whole bunch of superhero deaths, and probably a moratorium on the "revolving door of death" in the DCU--at least for a little while.
The question I have is who'll be coming back? First priority, I think, are the people who have died in the course of the story: Hawkman and Hawkgirl, Gehenna, Tempest, Damage, and so forth. After that, I suspect it'll be the really significant characters: Aquaman and Martian Manhunter will be back in some way or another, Ronnie Raymond, and the other obvious ones. I'm curious, though, how far the resurrections will go. Might we see a return for obscurer characters like Azrael and Conduit? Could Ted Kord and Max Lord--and other characters with significant event-specific deaths be on the way back? What about civilians, like Tim Drake's parents?
The real ballsy move on DC's part, the twist that would make a real interesting impact on the DCU and would show a commitment to shaking up the status quo (in the same way that New Krypton and Dick-as-Batman do), would be to resurrect everyone. We've already established that the only corpses which become Black Lanterns are ones who have particular emotional connections to our heroes, so it's not as if we'd have billions and billions of people returning (with the exception of resurrected planets like Xanshi)--that would make for a very crowded Earth. This would be an interesting way to lead into the "legacies" event that Dan Didio has talked about for next year--though they could do that with just a hero/villain resurrection as well.
But imagine a world where Thomas and Martha Wayne are alive again decades after being gunned down in an alleyway. Would Alfred tell them about Bruce's secret life? Would they get to meet their grandson? What would they think if they, knowingly or unknowingly, found the cave? What would they think if they found out that their son was dead and hadn't been among those resurrected? The same could be said for the Flying Graysons...how would Dick react to having his parents in his life again? How would they react to finding that their son had been adopted by a multimillionaire?
I think that would make for some interesting drama--although it'd kind of derail whatever independent paths the Bat-books (and several other books--what about Jor-El and Lara? Zor-El? Coast City?). It'd especially be intriguing to see what happens when Batman finally returns. How would the resurrection of his parents affect him? We've already seen him work to stop it (in "Tower of Babel"), so presumably he thinks it'd be an overall bad thing, but would it cause him to give up his crusade? Would he even be able to face them, given how their deaths have affected him?
Or would he return to find that they'd been quietly murdered again by the man who's wearing his face, Tommy Eliot?
In any case, I imagine that Blackest Night, if not leading directly into the return of Batman, will cause more than just Tim Drake to think that he must still be alive. At least some of the heroes will have to be wondering why Bruce wasn't among the resurrected/Black Lanterns, especially when his grave was among the first to be defiled by Black Hand. Obviously a Black Lantern Batman would be a great asset to the undead hordes, so it doesn't make sense that they'd leave him be. Someone is going to notice his absence and draw the likely conclusion that he must not actually be dead.
And if no one does, then I imagine that the heroes of the DCU are a lot denser than previously suspected. Come on, Detective Chimp? The ghost of Ralph Dibny? Someone will have to connect the dots.