So This is Concerning
With the benefit of hindsight, I think it's pretty clear that the 2006 elections represented a rejection of the ruling Republicans rather than an endorsement of the Democrats. This was probably also true, maybe to a slightly lesser extent, of 2008.
I also think it's clear that 2010 will be a (possibly really huge) rejection of the Democrats rather than an endorsement of the Republicans, who are still very poorly regarded per public opinion polls. (This will get worse, not better, when Speaker of the House John Boehner and/or Senate Majority Leader Mitch McConnell are on TV every day.) The biggest commonality of 2006 and 2010 seems to be that the opposition's voters are intensely fired up, while the majority's voters are severely demoralized; I could look this up and link it, but I'm not even going to bother because I'm so sure it's true.
So the Republicans are going to take majorities in or both houses of Congress. Yet it doesn't seem like anybody seriously thinks that they have an agenda that will get the country out of its economic rut, or do much else other than "investigate" the White House, block everything the president or minority Democrats propose, and maybe--y'know, for giggles--shut down the government again.
I guess there's an argument to be made that a Republican Congress and a Democratic president both up in 2012 have a shared interest in building a record of accomplishment, but I doubt anyone actually involved will see it that way; the Republican electorate views Obama as fundamentally illegitimate, and that will be reflected in a newly swelled Republican caucus filled with people who will make their 1994 class look like a bunch of squishes, while the Democrats will look to fire up their currently demobilized constituencies in advance of 2012 by highlighting the evils of the Republicans. At best, they'll all be hoping for an economic turnaround without great conviction one is on the way.
If I had to guess, I'd still bet that Obama wins re-election, and maybe the Democrats make some gains. But this is almost incidental to the larger problem: neither party, nor the executive or legislative branches, has anything like the support and confidence of the public. None of these entities or institutions is widely perceived as having any use other than as a vehicle for expressing unhappiness with the other side--like the Democrats four years ago and the Republicans this year.
How can this end well?