Bush, at least, doesn't seem to be headed in the "we do not torture" direction. And I do think that without him, it would be very difficult to move the Republican Party on this issue. The only other hope is that an explicitly pro-torture presidential candidate gets clobbered -- which certainly is a plausible scenario in 2012 -- but even then, it's more likely that the Rush Limbaughs and Marc Thiessens of the world would interpret such an event as a sign that the candidate wasn't sufficiently strident on the issue. There are to be sure quite a few conservatives who oppose torture, but fewer and fewer of them are candidates for elective office. Barring something new (and Bush could still flip, after all), I think a pro-torture candidate and platform is virtually certain for the GOP in 2012. And we know how the nomination process works (in both parties): candidates who are in reality basically similar in their positions on public policy are driven to differentiate themselves by taking high-profile extreme positions on symbolic, highly visible issues.
In my view, this embrace of torture - it is simply insane to describe waterboarding someone 183 times as anything else - is why the GOP needs to be defeated as a political force in its current incarnation. It is on the side of barbarism. It is an assault on America and the values generations of Americans fought and died for.