I think the chances for the repubs is better if Trump doesn't start that 3rd party and whoever the GOP nominee is will be elected the next president. And I highly doubt that person will be Donald J. Trump; he made too many enemies and is in process of making even more enemies as we speak.
I like your thinking and agree generally ---- but mine is simpler. I think Trump has been struggling -- with age, let's say -- since the election, and I don't think he'll be running for anything in 2024 based on that. I know, there are people older than he is by some years thriving in the Senate, but still ---- it's got to be uncommon.