I think it's more the matter of them having to accept her because if they don't, then that provides even more ammunition to the GOP. ie not only does their current leader have to bow out but the 2nd in command isn't up to the task either. Which piles onto the question of who exactly has been running the country for the past 4 years?Can it be that easy that all the key Democrats will just accept Kamala as Biden's successor?
Will some prominent Democrat(s) step in and challenge Kamala?
After all, if there was a primary contest there would have been a serious challenge to Kamala. We know VPs often do not come up on top when seeking the Presidency.