Doug Jones is DOA....
So Dems would need to take at least 4 to put the Senate at 50-50 and 5 to take control (because Trump ain’t losing).
And other than Collins being taken out for her vote for Kavanaugh. I don’t see any other GOP being in any real threat in 2020.. unless some scandal would pop up or something.
So, my guess is, Jones is replaced by a GOP, and Collins possibly being flipped... for a wash. McSally would be a wild card since she lost before, incumbency may not be enough for her to hold the seat..
So, worst case, Dems net +1.
Udall will be an uncontested seat, so that’s a possible opening for a GOP pickup.. to make 2020 a wash.
I believe Trump will have (barring anything unforeseen) very long coattails for the 2020 elections. KAGA!