Trump may have a physical incapacity. Not one of us can be sure that something will not happen to him, or any one of us.
"Plan B" for me is going silent and surviving the civil war that would be coming in the aftermath. Might be the same plan if Trump wins the "election" of 2024 too.
As you noted, "Not one of us can be sure..."[of anything, really]
One must adapt to the changing times.