To whom would she lose to? Trump will flame out, no one, including himself it seems, wants Jeb anywhere near anything and Walker went from hero to zero faster than Perry did last cycle. The rest are a collection of clowns and one nobody, none of whom would be able to seal the deal 10 years ago, let alone today. Hilary might have problems, but losing the general election isn't one of them.
People forget that the polling difference between Obama and McCain was within the margin of error for most of the race...until he selected Palin as his VP, which is double good news for Hilary, because a) she won't make the mistake of selecting Kanye West as her VP, and b) the kind of right-wing lunacy that Palin (and the current clown car) espouses has been firmly rejected by the general electorate.
Honestly, with distance, W starts looking a little more impressive, not just for not being quite as insane as his party (then or now), but for having at least some of that extraordinary political quality that enables stupid ideas or political non-starters to be more palatable.