If Trump loses this time but grovers back in the next election, then the post-Trump GOP is still eight years out.
Trump voters aren’t going away, and we won’t be voting for any GOP 1.0 candidates.
Not sure that there would be a next time for Trump if he loses this time. Biden is on record saying he will let the DncOJ pursue Trump, which it has been trying to do for years already. A Democrat executive branch will apply the full force of the federal government and deep state courts to destroying Trump, his family, anyone who worked for him, etc. They have been trying for five years so it’s not really a secret what their intentions are.