If the lunatic (and ascendent!) right wing of the Republican party manages to purify the party of any tendency toward "moderation," or traditional, 'moderate Republicanism,' what is going to happen when today's moderate Republicans become tomorrow's conservative Democrats? The smaller and nastier the Republican party gets the happier I am: it's correspondingly less relevant to a majority of voters. But, I'm NOT so happy with seeing the heterodoxy and fractiousness increase among the Democrats, whose party just barely finds common ground, today, e.g., the freak'n health care bill has been as endangered by "moderate" Democrats as by petulant Republicans. And a THIRD PARTY? You may think you want to go there, but I'm not sure you do: we're already unhappy with pluralities deciding elections. Do we really want a president elected by 31% of the vote? (Somebody else figure out my math. I admit childlike incompetence with such things.)
But, if we did see a smaller, even more intensely fanatical Republican Party, would the Democrats be forced to split into more than one party? Would there be less dissaray and more focus across the spectrum if there were a truly 'liberal' party to the left of a conservative (not right wing) 'Democratic' rump? Ugh.