The only way out is for them to lose so badly and so repeatedly that they lose any credibility even with normies and folks just openly call them cranks, forcing them to discard the narrative. It will take a while.

even if trump lost by 20 points movement conservatives would explain it away as a fraud caused by some combination of illegal immigrants, mail in ballots, and persecution by the courts

Basically Trump needs to get his ass beat and then whine about it so petulantly that even his fiercest defenders start to call him a baby. The one thing we have going for us is he will absolutely play his part.