Never say "never".
My eldest daughter was home two weeks ago, and went off on a remark she read about Bush 2 being "the worst President in history". "First," she said, "we need at least 50 years of perspective to evaluate a Presidency, so it's jumping the gun to call Bush the worst. And second, Warren G. Harding." (That's my girl!)
She said she won't be voting for McCain, either.
We'll have a Republican in the White House again, unless the Republicans go the way of the Whigs, which doesn't look too likely to me at this point, or unless the Emperor takes over.
Personally, I'm holding out for the spiritual heir of Teddy Roosevelt.