the thing is, Trump hates admitting he made a mistake. loathes it. abhors it. straight up denies he has ever made a mistake. having Vance step down as his VP nominee is basically an admission by Trump that he fucked up by choosing him. and he won't do that. so if Vance does get shitcanned, the song and dance they go through to make it happen is gonna be fascinating. they're gonna have to concoct some reason for Vance to make it look like it was his decision. and if he does follow through and resign like a dog, any aspirations he has of ever being POTUS are gone. kaput. he'll always be the weak bitch that Trump got rid of.
but if Trump doesn't get rid of Vance and then Trump loses, Trump will throw Vance under the bus. and again, no POTUS for Vance ever.
JD's only real option is to stick with Trump and pray they win. but if Trump tells him to resign, what's his play? he doesn't have the stones to say no, does he?