I think if the SCOTUS agrees that the 4 states violated the equal protection clause, which they most certainly did, then their electoral votes will be tossed.
Then neither Trump or Biden has the 270 votes required.
This will make the 50 state houses vote for President, one vote each. Good news! Republicans have the advantage here. Trump wins.
Who and how is it decided which way that one state votes goes? MI, WI, PA and GA could still decide there one state goes to what they certified and that would be biden.
Before that, why wouldn’t SCOTUS send it back to those states’ legislatures to appoint electors, as specified by the Constitution?
At which point we’re placing our trust in Republican legislators who have already demonstrated their disinterest in taking a principled stand.