I can't see how either party can even think about it right now until Democrats resolve their internal issue over who they will nominate. Sure, Biden's in the driver's seat right now but that can change the day he makes his next major gaffe. And Jill won't let him as long as he can keep getting both his presidential salary as well as control over the $200 million in campaign funds, even as donors are trying to freeze almost half of their pledged contributions.
This, more than anything, will be the reason Biden is forced to drop out. The question will be whether or not those donors will be willing to support Kamala with that money, or hold it pending if and when a new candidate is named at the convention. And the wealthiest liberal donors will likely hold off releasing that money until they see how Biden's replacement handles his or herself in a debate against Trump, assuming he's willing to even do another one.
But Trump will hold all the cards now in laying out the ground rules this time.