Assuming no special elections in the new seats.
AL R
AK R
AZ Most likely D
AR R
CA D
CO D
CT D
DE D
FL R
GA Probably R
HI D
ID R
IL D
IN D
IA Possibly D? They'd of been elected in 2018.
KS R
KY R
LA R
ME D
MD D
MA D
MI Possibly R? They'd of been elected in 2016.
MN D
MS R
MO R
MT R
NE R
NV Probably D
NH D
NJ D
NM D
NY D
NC Possibly R? They'd of been elected in 2018, but Republicans managed to win more House votes in the state that year. This one is iffy.
ND R
OH R
OK R
OR D
PA Most likely D
RI D
SC R
SD R
TN R
TX R
UT R
VT D
VA D
WA D
WV R
WI Possibly D? Would have been elected in 2020. A slight overperformance downballot from Trump could change this though. If the R Senate candidate were to outperform Trump by the same amount that John James did in nearby Michigan this would be an R win.
WY R
Ones I am not super sure about are IA 2018, NC 2018, and WI 2020.
In this case that's 25 more seats for each party. Both parties would have 75 seats. Harris would still the tie breaker. If the Democratic candidate were to win in NC 2018, with IA and Wi and every other state the same, then it is 76-74, but Manchin would still in a similar position.
The thing is that no dem ran in nc-3
