None of the current court cases have any merit and are being dismissed out of hand.
As I understand it they can’t change the method of picking electors after the election has taken place. Only if the result is unclear or a choice was not made (whatever that means) can the state legislators go down this route. As there is no ambiguity with the result anywhere their act would be unconstitutional.
This would wind up in the supreme court, which is obviously Trump's plan, and they would have to rule against a clear election result. And this would need to happen in three states probably. If it got this far the supreme court would be delegitimised, the electoral college not fit for purpose, and the republic would basically be gone. Riots and general nastiness all around henceforth.