Early voting is going to be very interesting in terms of total returns and breakdown by party, and comparing that to Election Day returns. There has been a small uptick in Republican share of mail-in voting. 

Democrats will never again get the vote by mail volume and splits of 2020 for obvious reasons, and likewise Republicans with never get their 25+ point advantage on Election Day ever again. 

There are so many unknowns that it really defaults back to what everyone has been saying already, turnout is what will win this election. 