My question is… would Trump even choose to participate in the debates if he (inevitably) wins the Republican nomination? He’s refused to even engage with the primary debates in his own party and is still leagues ahead of any other candidate in the polls.

If he doesn’t, I hope Biden takes part anyway and that Trump gets empty chaired. They could either invite some third party (Libertarian, Communist, etc) or independent candidates to give Biden someone to debate with, or give Biden a fully uncontested soapbox to ramble with the debate moderator. The latter would be hilarious to watch and would truly show what a farce this election is becoming.