Vance will struggle to control the cult, when Trump could just rant and they'd make up stories to justify it or ignore it entirely. They will still vote and swing together but without the control you will lose a lot of the people who weren't political before Trump. At least that's my guess.
Sadly, I do not believe the people controlling the far right including voting regulation intend to allow fair voting again. The MAGAts are not the only power they have. They at least nominally have control of the military and much of the court system, especially the one that counts most.
That is the route they are going to go, but once MAGA feels betrayed their penchant for domestic terrorism is going to show itself very brightly. They radicalized that base and controlling it is a must to prevent that and that's a tall order without Trump.