Should Biden “win”, the Senate must refuse to move any legislation of his at all, and absolutely must not confirm any nominee of his, whether administrative or judicial. But then there’s McConnell, and what would certainly be his absolute glee in trying to show how “bipartisan” he was, so there goes that idea...
Then you can look forward to some Republican Senators that live in States with Democratic Governors to begin looking for ways to get out of office alive.