I think you misunderstand what Trump represented and what it will do to the party. He replaced conservatism being the driving message with populism. He was the anti-politician. That sentiment isn't going away any time soon.
I agree but with a big caveat - this is a unique strain of populism manifested in the worst possible way - total commitment to a person, rather than a set of ideas. There's no way Tom Cotton or Nikki Haley or whomever can just step in and be the next populist MAGA champion.
Trump is the bridge that unites a very disparate group of people in a unique way. That is simply not replicable without Trump. That doesn't mean it's going away by any stretch - but it's not a durable populist movement IMO as long as Trump's ego is at the center.