And we know (because she told us so) that JKR was very careful of the wording of the prophecy. If we've learned nothing else from the books, the "obvious" answers to her mysteries are never the right ones.
The "obvious" view is that the prophecy applies to two people -- Harry and Voldemort. But why would JKR have to be so careful about the wording of that? It's so obvious that everybody would nod and say, "well, of course." The whole tension of the series would come down to Harry setting up his big fight with Voldemort ....yawwwwnnnnnn.....
No, she had to be careful about the wording of the prophecy because it does not mean the obvious thing. It means something unexpected.
You could be right when you say it'll be Neville, but I don't think so. I think Neville dies as Voldemort goes for the twofer: making sure that the prophecy really didn't apply to Neville, and also continuing the strategy of getting at Harry via his friends. Alternatively, Neville's increasingly impressive record of reckless bravery will prove to be his undoing, as he charges in to save Harry in a bad spot. Either way, poor Neville's a goner.
One of Fred and George probably die also -- at the wedding, probably. Ron was no doubt slated for death (playing the same role as Neville) but I think that with Neville dying, Ron gets a reprieve.
I really need to go back and read the books again. I picked them up and read them thinking they were children's books and by the time I got to the end of HBP - I realized there was more to them than that. You're right about the obvious answers and not taking things at face value in her books - you've probably nailed it regarding the prohecy. It's something I hadn't thought of before.