Indeed, this is also like the chaos that accompanied the self-destruction of the american Whig party before the civil war. My guess is that the republicans will become a loud irrelevance by 2020 and cease to exist after that while the democrats (which are not really a party either, simply everyone who is "not republican") will split into a few factions, two of which will be strong enough to be parties (probably one still called "Democrat") by 20204/2028.