Nope. The same people who are currently saying they'll never for John McCain will be singing a different tune come 2008.
"Well, I'm voting McCain to stop Hillary."
Thus the cycle continues.
List of republicans I'll NEVER vote for, period:
John McCain
Rudolph Giuliani
Condoleeza Rice
There are so many good, conservative republicans who are making the moves to run that it's absurd to me personally to even consider the three above.
How could I forget Chuck Hagel? Add him to the list above.