... Now if they just don't lay down and take a nap
I'm not sure that the Democrats will be able to pick up any seats at all in the house during the next election. They might be gaining ground now, but that probably won't hold. The only thing that will help the Democrats is if the Republicans continue to shoot themselves in the foot. Fortunately they seem more than willing to do just that.
The only problem is that the Democrats themselves are becoming a real problem. Without the Republican party to challenge them, the Democrats are really slipping toward problems. By the time they actually lose, the Republicans might actually have rebuilt their party to the point where they will control the United States for an extended period of time again.