I don't believe there is anyway Biden doesn't move into the White House in January. My only hope is that the clusterfuck of this election will result in uniform voter registration and voting policy (voter ID, absentee ballots while eliminating the mail in disaster). Although Trump may have a better chance of serving his second term than that happening, with Pandora's Box being blown open.
Well, unfortunately, any type of universal voting rules for the country are going to be highly unlikely with a divided congress.
The problem with voting reforms is the side that just "won" rarely wants to change the system that elected them. So for example, when Republicans won in 2016 and had control of both chambers of Congress and the Presidency, voting reform was barely on the radar. Yes, Trump rambled about the "millions" of illegal votes happening. Hell, he set up a commission to investigate (remember all that?) only to find so little evidence that it faded to nothingness.
So without hard proof of voter fraud, something that holds up in the courts, journalistic scrutiny, and public opinion, I doubt we change the system that states have most of the power in election results.
I think if there are any changes, they have to come at the state level. You might see a LOT more states (PA, Wisconsin, Michigan) follow Florida in being able to start to count/verify mail in ballots before the actual election day. That way, they will mostly have their results done by midnight on election day itself.
I mean, we see that it is not ideal to START counting mail in ballots once the polls close and the workers become available to start opening, verifying and feeding millions of mail-in ballots starting at 9PM at night. It becomes an entirely different shift of workers and people. Very hard for election commissions to do both, especially in busy locations (cities, polling places with problems, etc.).
Mail in voting isn't going anywhere. With record turnouts (for both Democrats and Republicans) and with Republicans doing well in down-ballot contests, I'm not sure either side is going to say "let's stop mail-in ballots".
There will be better, more consistent rules ABOUT mail-in ballots on the state level and maybe re-looking at ways to get results out faster.