Solid and boring with no chance of winning:
- Ted Cruz
- Marco Rubio
- Mike Lee
- Cotton maybe
Trump Jr. absolutely runs. His viability will be determined by Biden's performance. It's hard to go back to crazy if stability treats you well (a rule of thumb many divorcees have shared).
John James will be groomed for the nomination, but he needs to govern first, so 2028 is more likely for him. Although, Buttigieg went quite far without any experience and James is eminently more likable that Mayor Pete, so still plausible.
But odds end favorite is Pence. He will carry the Trump vote and he's an actual adult who will attract moderates. Pair him with James as a VP choice and that's a pretty decent ticket for 2024.