Can The GOP Follow The Tories?

A reader writes:

At what point does the wingnut Republican base become so politically undesirable that the Republicans will do something about it?
When does the GOP make the deal that says, OK we'll give you common sense drug laws, Civil Unions, non-hate-based immigration rhetoric, separation of Church and state, acknowledge climate change, show reasonable efforts at gun control, and make our case to America on limited government, balanced budgets and the Powell Doctrine?  Send the Falwell/militia wing packing to form their own party, and let the grownups try to suss out the real problems
How much of the "base" would desert?  Would social moderation and basic common sense turn enough independents to make it worthwhile for them? 

It will happen. But it may take a couple of election cycles.