National anti-incumbent sentiment means a dozen or more House seats will go—which sucks, but many of these House seats belong to Democrats who don't have the balls to vote like Democrats when it actually counts, so it could be more or less a wash.
Meanwhile, the RNC blew all its money on winning two close Gubernatorial races last year—and they lost what should've been a safe Republican congressional seat. That loss, which happened because Tea Partiers hijacked the race, could be replayed across the nation: Tea Partiers are launching primary challenges against NRCC-approved candidates in various districts.
In Florida, a "true" conservative Republican candidate for Senate is dragging down popular moderate Republican Governor Charlie Crist.
Basically, a hell of a lot happens over the course of a campaign. Of course, without the magic 60 votes, there can be no movement at all on any major legislation, because the government is broken, but it remains to be seen if our 60 Democrats will manage to do anything at all on climate or financial regulation or immigration this year, or if they will just give up and pass a "deficit hawk"-sponsored additional massive tax cut.
The big problems will be voter enthusiasm and turnout: Organize For America/the DNC needs to energize the Obama electorate, and do something with their magical lists. Because black people and young people are, at the moment, not sounding like they'll turn out.
So! That is our analysis. Please keep it in mind when you read your next story on how there will be massive Democratic losses that will destroy the Obama presidency! (And please forget it if 1994 happens again! In that case, get ready for impeachment!)