If everything goes to shit republicans have nobody to blame because they have a majority everywhere and we can vote them out.
And the democrats got a wakeup call they can learn from (but they played the same 2016 tactics and got the same 2016 prize so we'll see if anything sticks next time)
That assumes there are no shenanigans with those elections. I believe we will have them (edited to clarify: I believe we will have elections as well as election shenanigans.) We'll just have to see how fair they are.