You folks realize the GOP is pretty much a sitting duck now? It's too late for it to evolve. Once a party is taken over by the most extreme elements, that's it. That's how parties die off.
If the GOP were to die off, then the Democrats would just be taken over by extreme elements and cause GOP to be resurrected, some other party to rise, or the Democrats to split. If there was no GOP threat, the Democrats would all be in the mold of Pete Stark or Alan Grayson. This would scare off the American electorate into voting for something else, perhaps an organized Tea Party.
The US political system all but guarentees two parties and whoever is in power will be subject to more scrutiny than the opposition. We will remain essentially a 50-50 Rep and Dem country until the system changes.