Your early 2020 Senate rankings

[Pericles]

I've decided to assess the races by national environment and have 5 different scenarios, R+4, R+0, D+4, D+8 and D+12 for the national environment(so don't confuse these with gains by parties, though sometimes they do align).

2020 Senate(R+4)
R 57+4
D 41-4
I 2_
100 seats
51 for majority

GOP gains AL, MI, MN, NH

2020 Senate(R+0)
R 53_
D 45_
I 2_
100 seats
51 for majority

GOP gains AL
Dems gain CO

2020 Senate(D+4)
R 50-3
D 48+3
I 2_
100 seats
51 for majority

GOP gains AL
Dems gain CO, NC, AZ, ME

2020 Senate(D+8)
D 50+5
R 48-5
I 2_
100 seats
51 for majority

GOP gains AL
Dems gain CO, NC, AZ, ME, GA, MT

2020 Senate(D+12)
D 54+9
R 44-9
I 2_
100 seats
51 for majority

Dems gain CO, NC, AZ. ME, GA, MT, TX, AK, IA

This is a bit rough and shouldn't be treated as a hard and fast guide, I could see Collins losing surviving in a D+4 environment or Republicans gaining an extra seat like NH in a neutral environment. But this is an overall assessment from me of the big picture.

EDIT: Maineiac told me Collins could lose in a D+4 environment, so I have edited my ratings.

[Pericles]

Dems would win KY or KS after NC and AZ not TX

Kentucky is pretty far gone for Dems, McConnell won by 6 even in 2008 and it's shifted a lot to the right since then. I could see Kansas as a pickup in a blue tsunami scenario. However Texas is trending Democrat pretty rapidly, Cornyn doesn't seem super popular and with a strong candidate and presidential year turnout it is gettable for Dems.

[Pericles]

He's smarter than Cruz, Cruz had one of the worse presidential runs ever.

That's a bit too far, Cruz came second in a 16-person field.