One of the two snags I've hit so far is deciding on what to do with Ginny.
My own thought would be for Harry to rescue her (he -is- a Hero, after all ;)), but for Tom to have leeched off her to such a degree that her magic/core is temporarily (or permanently, if you're really feeling mean) inhibited to where she's not much more, if any, than a squib and she won't be returning to Hogwarts for a while, if ever. The side effects of this with Ron could quite possibly drive a further wedge between him and Harry, likely much to his loss.
just my $0.02.