The problem is in the contemporary GOP only cynical manipulators and true believers can rise to the top. And the cynical manipulators end up being so transparently dishonest that people don’t trust them (Romney, Guiliani, Gingrich, Pawlenty, Cheney, etc) or they are adults who sincerely believe in all the conspiracy theories (science is a global anti-christian conspiracy, evolution is made up) that they end up self destructing because anyone who believes those kinds of things is guaranteed to believe a lot of other stupid things that makes them seem too unprepared or extreme to be trusted with power. Huckabee, Bachmann, Cain, Paul, Perry, Palin, etc.
But I wouldn’t be surprised if they win. No matter how extreme they get they can gather up 40% of the vote. All it takes is democrats staying home combined with some independent voters siding with the GOP for another sweep for them to win.
I guess in the long run that is good, the GOP when it does win (like it did in 2010) assumes it wins because they are rabidly conservatives, not because their opposition stayed home. This speeds up the downward spiral and hopefully some party restructuring someday.
I’d like to believe by the 2020s the GOP will be a regional party that can only win 45% of the vote at most in national elections, but who knows.