“Allowing Trump’s successor to emerge and be developed at a later time,” as George W. Bush did by picking someone like Cheney, would be a disaster if it resulted in another McCain or Romney. No thanks. Pick a real conservative, relatively young, and make him the favorite for 2020 or 2024. (Pence is 57.)
I do not think a President Trump would make the same mistake. I believe he will bring a lot of talent into the Administration and likely not one but several of them will emerge as serious future presidential candidates. People who we are not even talking about today as being major players.
So in Trump's case, he may decide to go with a seasoned vet for now over some young upstart. I believe he's always thinking well ahead.
They will very likely lose to one of Trump’s sons. The Clinton’s and Bush’s are not the only ones who can play political dynasty.