Not only will they not do that, but they will work with Trump to make middle class cuts permanent. They will pass some infrastructure spending.
We can kiss any chance of controlling spending good bye. (not that there was any) But Trump will get a few things and talk about them on the 2020 campaign trail. Then he will talk about the obstructing, resisting, one term and out, Democrats. The worst case for them is they try to impeach. They might not get the votes because not all Dems are that stupid. But if they do, he will release documents in his defense that will make a very good case to impeach Obama.
He will win in 2020 regardless, but if the Dems are stupid he will win in a landlslide with huge coattails.
I think we can forget about funding the border wall.