Their will be plenty on the table to choose from if Trump chooses not to run....I suspect some will say nothing until they know if or not Trump looks to run. Besides they always put out there all kinds of ‘feelers’ on both sides of the aisle. Even before announcement, they have to ensure that they have enough funding and sponsors to make it through the campaigning process.
I think Trump will run again and win, but he can only do that once. And from your lack of a name, I see you have no speculation as to who will be next. Just “not Paul” because his father or something.