Highlight from discussion:

If SCOTUS decides to take the case AND rules in favor of Texas, the remedy would be for the State Legislatures from Pennsylvania, Georgia, Michigan, and Wisconsin to select the electors. Should the Legislatures decline to select their electors, it could go to the House of Representatives under the Twelfth Amendment. If neither candidate reaches 270 electoral votes, each state has ONE vote to cast for their candidate decided by a vote among the delegation of the state whereby the majority delegations in the House of Representatives are Republican. Presumably they would vote for the Republican candidate but that is not mandatory.