I think they could ultimately become the source of a viable Third Party, if Pelosi and Co. try to overreach and play LBJ-like games with the new Congressmen.
There is no way the Dem powers-that-be (the ones who kept Pelosi and Reid out of sight for the run-up to the election) will allow them to "overreach." They have another election coming up soon and I guarantee you the last thing they want is their leadership showing off its moonbat side. The plain fact of the matter is the Dems that won ran as "conservatives," so they've boxed themselves in to toeing that line. They know the electorate has little patience for their goofy side.