For redistricting, the main 2020 fights I see are these -
-OH State Supreme Court Seats
-MI State Supreme Court Seats
-MN State Senate
-NC State House/Senate
-NY State Senate Dem Supermajority
-AR Redistricting Reform Ballot Measure
-Texas State House (Court drawn map better than legislature map)
-KS State House, ending Republican supermajority to sustain Kelly's vetos
There's other things that seem like stretches but possible (FL Leg., Texas State Supreme Court, NC Leg. is kind of a stretch too) but the eight above are probably the most realistic and important.
Michigan will in all likelihood have a D majority on the Supreme Court after this election but it doesn’t matter because of the new redistricting panel.
It'll still be very much in Democrat's interests to control the court, both for redistricting and otherwise.