Trump is way too old to continue his political career. He can kibitz on twitter, but GOP voters know he's damaged goods, he'd never make it thru the primaries. The young guns now get what it takes to win, and they don't have any baggage. In 2024 Kamala will not be electable, so any reasonable GOP candidate should win easily.
If Trump forms his own party he'll get fewer votes than Ross Perot did.
Why do you think that Kamala is unelectable?
Who is a "reasonable" GOP candidate? Don Jr. ? Ivanka? Jared?
Kamala is the most leftist senator by far. Her policy positions would not be supported by the majority of voters.
The top candidates for the 2024 GOP nomination? How about:
Ted Cruz (2nd in 2016)
Mike Pence (the softer more electable version of Trump)
Nikki Haley (fresh face and a woman)
Marco Rubio (just ok)
Rick Santorum (experienced loyal GOP soldier)
Rand Paul (hard core)
Kristi Noem (S.Dakota governor & female, good VP pick)
Mike Pompeo (super smart)
You could throw in Don Trump Jr for "Auld Lang Syne", but I'm not hopeful the GOP wants any dynasties formed.
My personal favorite is Elon Musk, but I'm not sure his citizenship status is constitutional.