Seems reasonable. May be overestimating Ernst and overestimating Dems in the South outside of NC and GA. Other than that this is my map. I assume Collins won't be the nominee in maine.
Beating Ernst (or any incumbent Senator in IA, for that matter) isn't going to be easy, she's actually more popular than you would expect and will likely outperform Trump. It would really take a big wave to beat her IMO.
If 2020 is a burbstompin', several Southern states could fall, which is why I only rated them Likely R or Tossup. NC, GA and TX are obvious, but Dems could also put MS (with Hood), LA (with JBE) and SC into play.
I was also thinking about rating MT Lean D with Bullock given that the NRSC seems to have given up on winning Tester's race, but I still think Daines could win in a more neutral year, despite all his flaws. That said, even if Bullock declines to run Daines will be vulnerable, particularly if Tester wins big next year like most people expect. So Tossup/Tilt D (with Bullock) and Tossup/Tilt R (without Bullock) would be my rating at this point.
