A year to have many things happen one way or the other. No doubt they could lose a few house seats.If I was in the upper reaches of the Republican party, the election being so close despite the district being long time GOP stronghold and the Dem's candidate being from outside the district would worry me about 2018.
But there are also some vulnerable Dem Senate seats up as well. In very GoP states.
In the end it's too early to worry about them. They need to get some legislation through and accomplish things. The Dems have a lot of issues on their plate as well.
Nancy Pelosi being first.