The Republican Party was born in the Tea Party of its era as a third party in 1854 out of the northern Whig Party, so if the Republican Party disappears in the next few years, it wouldn’t be the first time in American history something like this has happened.
Personally, I think the GOP establishment will either jump on the bandwagon, or pick up their marbles and go play with the Democommies.
Charlie Crist of Florida is a perfect example of the latter.
As you are well aware, Crist is but the latest and most prominent example. The GOP is about to receive an enema.