I could definitely see the Republicans splitting within the next decade- the Santorum crowd keeps hogging the discourse, and the Huntsman/Romney coalition of the party say "screw this, we're out of here".
Bottom line: sooner or later the Santorum crowd of the Republicans will spin itself into irrelevance. That is incontrovertible. The question is when it will happen.
Here's the thing, kids, and I say this as the son of a historian. Liberals cannot win right now. What we are going to have to accept that we're doing for probably the next two decades is that we're not dominating the national discourse, we can't currently dominate the national discourse, and the best we can do is play the waiting game.
I think, too, that liberalism is starting to shoot itself in the foot and needs to remake itself. The Left (communism aside) in the 20th century focused on the social safety net, and that's a battle that it won, in some cases all too well- I'm as bemused by the absurdity of European pension plans as any (moderate) conservative. The last major real battle that needs to be won on that end is giving America universal healthcare, and Lord willing and the creek don't rise, we'll have won that within the next decade. Right now what we need to do with the safety net is to make sure that it's economically sustainable, that it doesn't pay out more than it really needs to, and also that (in the case of welfare) it pays people to learn marketable skills rather than just handing out unemployment checks. Obviously things like housing subsidization, food stamps and the like need to be kept. But by and large, kids, we've won the great battles of the 20th century. They're being tested right now, for sure, what with right-wing crazies trying to turn the clock back to 1890 and with the great demographic booms of the century getting into the twilight of their years, but they're not going to be dismantled wholesale. We need to figure out how to make them smarter, for sure, but we're not going to get rid of them.
What will the great battles of the Left be in the 21st century? Cautiously, I argue that they'll be global warming and the dethronement of the corporation. Social issues right now will be little more than a footnote. They're important, to be sure, but above all else what's going to be needed is a change in the American cultural climate. That's already happening- most kids are less homophobic than their elders- and you can't do much to legislate it along. Global warming is a crapshoot right now, and I doubt we'll do much about it until there's either a major famine somewhere or an important part of the First World is flooded. As for the anti-corporatist crowd, one of the things that worries me about OWS and its ilk is that they don't offer much in the way of alternatives. It's very easy to just propose dismantling the modern corporation, and the easiest part of the battle will be, in fact, dismantling it; but most people in the Western world work for a corporation, corporations drive most economic growth, and I'll want to see some actual, constructive alternatives before I'll sign the bill that shreds them. It can't be a command economy- everyone has accepted that since the Wall came down. And there are some jobs so huge that only big somethings can possibly take them on. I don't know what those new somethings are yet, but you can bet I'll want to see a few ideas before destroying the current somethings.