if Voldemort's AK against Harry had hit. Would Harry have survived it, the way he does in book seven, with a third Horcrux destroyed?

Edit: and something else I just thought of. If you look at this from Voldemort's PoV, you have to say that it's an abysmal failure and a massive setback. Prophecy lost, most of his competent DEs captured, and his cover blown at last, everyone knows he's back now. And for all that he gets exactly one dead OotP member, who was stuck in his house anyway, and taking up the attention of the Aurors besides.

As such, while the readers and Harry obviously won't see it that way because of Sirius' death, it has to be considered a massive victory for the good side.

So why is it, then, that the aftermath in book six makes it seem more like a victory for Voldemort, and an encouragement to start up more daring plots? I suppose he could have done those more daring plots during book five already, as soon as the Azkaban breakout happens, but he was waiting because for the prophecy he needed stealth which once lost he couldn't regain - because he wanted to take out Harry before doing anything else, and needed the prophecy to be sure how to do so. And then once the prophecy is lost and his cover is blown, he's forced to forget that plan and move on, which works rather well for him as the good side is totally on the defensive, at least openly, in books six and seven until the end. But at the very end we see the proof for why his plan A was indeed the better plan after all (though the prophecy wouldn't have told him all that much useful, but then he can't know that).

And still something else: can anyone make something of the two fragments of prophecy we hear? It's tempting to think they're relevant, but they're so short that it's fairly hard to tell.