In all likelihood, if Trump loses, the Neocons will re-exert their power over the GOP and will be picking the future presidential candidates that conservative voters will be allowed to vote for. Maybe they will be a bit edgier or more bombastic, in a shallow attempt to emulate Trump's style rather than his substance, but they will be Neocon DC establishment guys who take their orders from the same people pulling Joe Biden's strings. Trump was a unique phenomenon and that phenomenon will likely die with his political career.
Though, whether Neocons or more ideologically true, I don't foresee there ever being another Republican president after Trump.