How will Obama overcome an Ohio and Florida loss?

[Verily]

How can he still win when he loses those, and there's a decent chance he might lose them according to the polls right now. He might win states like Colorado and Virginia that used to go Republican, but that doesn't add up enough to make up for the eventual big losses. So how is he able to?

Hmm? If Obama won all of the Kerry states plus Colorado and Virginia, he wins. He wouldn't need either Ohio or Florida. You've answered your own question.

[Verily]

Colorado and Virginia (and Iowa, Nevada and New Mexico, which also seem to be favoring Obama generally speaking) are not by any means "solid GOP states". With the exception of Virginia, Kerry did better in all of them than in Florida!

Of course, the reality of Florida is too complicated to go into, but I daresay it is a "solid" GOP state (or at least more so than many states which actually were not as close in 2000 or 2004), with Gore in 2000 nearly winning it in what might be considered extremely ideal circumstances for the Democrats in the state.

[Verily]

Scenario 3 doesn't need Alaska to flip for Obama to win, in which case it is a reasonably likely possibility for an Obama/Warner ticket (or maybe Obama/Webb or Obama/Kaine, although both combinations are IMO less likely to deliver VA).