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.