Democrats will be gaining seats in the US Senate in 2020,2022,and 2024.

2020
Democrats will hold onto
DE- Coons-D
IL- Durbin-D
MA- Markey-D/Kennedy-D
MN- Smith-D
NH- Shaheen-D
NJ- Booker-D
NM- Lujan-D
OR- Merkley-D
RI- Reed-D
VA- Warner-D
Democrats will lose
AL- Jones-D
Democrats might lose
MI- Peters-D if Trump-R carries MI.
Democrats will gain
AZ special(McSally-R vs Kelly-D)
CO(Gardner-R vs Hickenlooper-D)
NC(Tillis-R vs Cunningham/Smith-D)
Democrats will have a net gain of 1 to 2 seats.
2022
Democrats will hold onto
CA- Harris-D
CO- Bennet-D
CT- Blumenthal-D
HI- Schatz-D
IL- Duckworth-D
MD- Van Hollen-D
NV- Cortez Masto-D
NH- Hassan-D
OR- Wyden-D
VT-Leahy-D
WA- Murray-D
Democrats could lose
AZ- Kelly-D vs Ducey-R
Democrats will gain
NC(OPEN Burr-R)
PA(Toomey-R)
WI(Johnson-R)
Democrats will have a net gain of 2 to 3 seats.
2024
Democrats are endanger of losing
MT(Tester-D)
WV(Manchin-D)
Democrats could gain
FL(Scott-R)
TX(Cruz-R)