I've been thinking about this quote from E.D. Kain recently, and I think it applies:
The Democrats have Obama, and without him I’d say they stand a much less likely chance of holding on to power unless, of course, Obama cultivates a strong following within the Democratic leadership – but we’re only half a year in to the new administration. In four years, if he is as skilled a politician as he seems to be, he will have remade the party in his own image, and that’s dangerous for conservatives.
I think part of the reason why the Democrats in Congress kinda suck right now really is because it's still, in large part, the Party of Clinton. I think that the 2006 and 2008 elections were helpful in bringing in a more progressive group of people that hold promise. Sure, there were some really conservative inductees in those congressional classes, but there's a real difference between a Democrat like Bob Casey and one like Evan Bayh. Both are classified as "moderate" but Casey is, like most newer Democrats, an economic populist and Iraq opponent (though he is socially conservative). Bayh is fairly liberal on social issues but is otherwise functionally conservative. I think this shift will continue, but even more than that, it's a question of attitude: Dems like Bayh, Landrieu, Nelson, etc., tend to be more deferential to the right wing because of the formative experiences of their careers, but more importantly, they tend to have a different conception of what it means to be a Democrat. To these folks, one can be a Democrat while taking vast amounts of corporate and special interest money. There's no conflict to them. Their careers began during a time when fundraising was difficult for Democrats without sucking up to those powers--something that doesn't really hold any longer, considering institutions like ActBlue and MoveOn and all the rest can raise money as well. Obama swamped McCain in fundraising last election. The game is changing.
So I think that getting something done now, then waiting and seeing and fixing what wasn't fixed before seems like a good idea. Leaders can have a dramatic impact on the future of their parties--just think of the GOP now and the GOP circa 2000. Or 1990, for that matter, before Newt Gingrich. Hopefully Obama will turn out better than those two.