I know your prediction on the death of the Republican Party was based on a big assumption, that it wouldn't change. But that's true of both parties. True of any competitive enterprise as well. Which is why I think this huffing and puffing by the Left over the purported shift to the right by the Republican Party is all rather amusing.
Has the GOP shifted rightwards? Maybe. I'm not a registered Republican, never have been, but let's use me as a proxy. Have I shifted right since January of 2009? Absolutely. The obscene increase in Government spending, the shocking increase in debt, the (in my opinion) blatant dis-regard of the markets and contracts and the bullying way Obamacare was passed resulted in me moving from what would be described as a moderate Republican to a Tea Party adherent. Notice what happened. I moved first. I didn't follow the Party. I moved and clearly I'm not alone.
So what has been the GOP's reaction to this movement by their constituent's move to the right? It moved to the right. It had to if, as you point out, it wanted to survive. This is why I find the criticism of the Tea Party and the rightward movement of the GOP as amusing. In essence, the Democrats are saying, not to the Republicans, but to the electorate, "You are stupid robots controlled by evil Fox News and the Koch Brothers." To me, they (and you) are mis-understanding, at the most basic level, why the GOP is where it is. The GOP is reflecting the wishes of Americans and the Democrats are insulting the electorate. FYI, insulting me is not the best way of persuading me.
I won't predict what happens in 2012. Maybe the Tea Party reaction will cause a counter reaction, which will cause another reaction, the dialectic process that brings us to the middle. You seem to worry about partisanship and paralysis. I don't. All that's happening is the country is trying to figure out its path forward. In many ways, it's like the market. Lots of individual decisions arrives at a consensus (or equilibrium in economics jargon) that splinters, then reforms via constant iteration to another consensus, and so on.