Trump will probably try to run again and his built-in advantages give him a leg up. That said, just threatening to run gives him all kinds of room to maneuver, so it may be impossible to tell if he is serious or not until the last minute.
Given that Trumpism seems to have worked for the party overall - the big money men can get their agenda passed as long as they let the party have its cultural resentment. They thought for years they had to dogwhistle those resentments but Trump proved the base wants it straight up.
If for whatever reason Trump himself doesn't run in 2024, other people are going to try and run the Trump playbook. (There will be people trying to run a "return to old-school Republicanism" but I don't think they have any chance to make up real ground.)
That said, where are our primary contenders for running as Trump 2.0?
Category 1: The Politicians
You need to have the ability to channel the outrage and bluster in a convincing way. Too much in the system makes you suspect, so a bit of outsider cred is needed. This is a hard line to walk and I think the least likely to work.
I'd lean Josh Hawley out of the current crop of GOP pols, but someone could suprise me. I can't see Cruz actually getting enough people to support him, same with Cotton. If Nikki Haley was a white man, she could do it, but I don't think they are ready for her to be outside of a Ben Carson/Herman Cain token role for now. She would need an extra boost to go over the top.
Catgory 2: The Dynasty
Don Jr clearly wants it and has basically all the tools. He also seems to have a cocaine addiction and that can fuck you up big time. It's his to lose, and waiting in the wings is Ivanka. She gets the boost of whiteness and the family name to overcome being a girl. She doesn't have the raw anger and resentment that her dad and brother do, though, and will need to work on that.
Eric doesn't have the extra oomph and Jared is a lightweight.
Category 3: The Celebrity
A huge part of Trump's appeal was "He is that famous business man from TV!" You would need a platform, some fame, and a good ability to channel the Trumpian line. Most of the Fox opinion hosts qualify and you can't discount the rumors circulating around Tucker Carlson. (I'd bet on him over Hannity any day.)
But a big element of the celebrity aspect of this is the idea they come from outside, and anyone already a new show guy is a bit compromised there. Someone completely out of left field - an actor, a CEO with some telegenic charisma, an athlete... these are all good candidates. It would be someone we don't see coming, because they've been posting a lot of shit on Twitter and in interviews and "joking" about running for a while and then will suddenly make the jump with a big media splash.
If Trump doesn't make it for 2024, I really think the "Celebrity out of nowhere" is the one who is going to sweep in.
EDIT: I should probably add Dan Crenshaw to the list of potentials in Category 1.