Trump was born a politician. He's just better at it than most, a natural who makes it look easy. And he's not the type of politician the R's are accustomed to supporting - an America-loving populist. But he is one, for sure.
"Who do you have in mind?"
Well, even Trump is not a candidate yet. He has time to repent.
But, ideally, there will be at least one candidate that promises a fight to Make America Free Again. If TrumpRyanCare, SwampVax, etc are what Trump means by the subjective concept of Great, then he leaves room for someone better.
Anyone running a successful business or organization is a politician by necessity, but he was never elected to a government office before running for president.