Trump will end up damaging the Republicans for years to come.
If they select him as their 2024 candidate they'll lose. It'd be classic case of trying to re-run a race that they lost this time, except in 2024 Trump will be older, even more deranged and the demographics will have continued to shift further away from the Trumpite theme of stoking the grievances of white men. Moreover, he won the first time because many people didn't know exactly what they'd be getting , which won't be the case in 2024.
The GOP are in great danger of making the same mistake as Labour Party Corbynistas in the UK: mistaking a passionate hard core of support for evidence of popular support across the country.
And even if Republicans choose a different candidate for 2024, their brand has been damaged by Trump and his hard-core nutcase supporters. And having Trump holding regular rallies, which he is likely to do even out office, is going to be a continuing damage-dealing factor over the next few years.