The Trump era is unlike anything since Reagan, so traditional losses will not materialize. With
Trump on the Stump (note to self; call my trademark lawyer), I'll bet on a complete wash. Republicans lose less than 5 and perhaps gain a few., which would be historic and emboldening for DjT.
At that point look for wholesale changes within Deep State (primarily State Dept. and Dept. of Justice)
I like that theme, chiller, Trump on the Stump! Nothing works better...
Flashback to the Can't Stump the Trump video series on Youtube.