Now, of course, some of these trends tacked back the other way in 2010 (although midterm elections skew older and whiter than presidential elections). For instance, Republicans closed the gender gap -- the Democrats' historic advantage with women -- for the first time since such exit polling began in 1982. Independents, who were key to Obama's victory, gave the GOP a surprise second chance.
But that's the point. In politics, demography needn't be destiny. It's more like a wind you can sail into or with, making your job easier or harder, but it need not determine your destination. By the way, isn't there something vaguely racist about the idea that, say, blacks will always vote liberal because, you know, that's what black people do?
The fraying of the Obama coalition wasn't a function of demography but a result of events (including, crucially, Obama's own decisions) and the debate those events produced. Now, Obama's poll numbers are ticking up after a good December, and that, too, isn't a matter of demography.
The only way for the GOP to make real progress toward becoming a majority party is by making and winning arguments. That's true of all political parties, but some more than others. The Democratic Party is dedicated to transferring money from people and institutions it doesn't like to people and institutions it does like. Since there will always be more "have-nots" than "haves," that puts the GOP at a disadvantage, which is why making persuasive arguments is so much more essential for conservatism than it is for liberalism, and why coasting on short-term demographic advantages is so much more dangerous.
If you do a straight-line projection from today and assume that everyone's politics hold constant, the GOP will be in big trouble, if not doomed, a generation from now. And that's why, after the celebrations are done and the hangover has worn off, the Right needs to get to work explaining why they're right.