He can win it (I mean, polls show that even Hillary can, if she can he certainly can.) That doesn't mean he'd win big, but neither did Clinton.
Edwards winning WV by a large margin would also have just as much to do with the GOP candidates being horrible fits for the state than his appeal there.
I'd say any state that voted for Clinton either time is winnable, except Georgia, Tennessee, Louisiana and Montana.
Polls also show her doing well in TN. I think, sadly, that Tennessee is winnable for the Dems. Bush is very unpopular here now - 60% disapprove. Georgia and Louisiana have undergone a much more seismic political shift to the right than Tennessee has. Montana is a wildcard