If the GOP were ever to dissolve I think you would see a return of the Southern Democrat as a new party rather than moderates vs. ultra liberals. You might also see an uptick in people who identify themselves as Libertarians as moderate former members of the GOP look for a new political affiliation. I actually think that a collapse of the GOP would actually cause the creation of a 3 party system with a far left party, a socially conservative and economically liberal party, and a socially liberal economically conservative party.
However, I doubt the GOP will ever really dissolve. They will just have to find some way to adapt to the new political and demographic realities of the country as we move forward in time. Right now there is a battle going on between social conservatives and economic conservatives for control of the party. This intraparty strife is being exasperated by the immigration debate and it very well could result in the GOP losing half of it's base voters depending on the Democratic response and the available 3rd party options.
I also keep in mind that the Republicans lost alot of influnice in the 1930s and also had changing demographics against them,I think we are seeing somewhat of the same thing in 2008,Then with the demographic changes the Republicans may lose the who entire Southwest over the next 15 years or so. So in order to counter this electoral change the Republicans need to become more competitive in states that became realibly blue after 1992 i.e. Illinois,New Jersey, and some other states. I think the South excluding Virginia and Florida will remain solidly Republican so in order to survive polically the Republican Party must embark on a Rust Belt strategy or something like that.
