If Trump falls, Vance will not have a free hand.
Unable to make enough people happy, Vance quickly falls.
Vance's only hope would be a completely clean cabinet with everybody in it smarter than he. Building a new cabinet with actual brains would not be hard to do, for anyone but a Republican.
Vance, being too stupid to get out of himself, will fail at that task.
And he winds up like this NAZI. Who was then obliged.