I don’t think I understand what you’re driving at. There is succession (for an executive that is removed by forces external to the govt such as death or assassinatio), there is impeachment for executives deemed unfit for office by Congress and there is article 25 for executives deemed unfit by their cabinet members.
For context, the 20th C saw 17 presidents hold office (counting both McKinley and Clinton who overlapped their respective turns-of-century). Of them 5, nearly 1/3, exited office prematurely and everything was fine. Through war and national tragedies the mechanisms worked.
This whole thread started with me saying that I would prefer to seee Warren at the top of the ticket with Bernie at VP. Yes, I understand the concern of someone so old attaining office, but a) he wouldn’t be at the top of the ticket, anyway (in my scenario) and b) there are plenty of mechanisms both internal and external to remove him if the need arises. However, as I said previously, he seemed to weather the campaign better than anyone else and had just as rigorous a schedule, of not more because he both campaigned for down-ballot candidates and has continued campaign-style rallies and appearances to this day in addition to his Senatorial duties.
Meanwhile, we are currently in a scenario where the executive is exhibiting behavior that, if it isn’t mental decline per se, is sure erratic and unpredictable and the government continues to run just fine (even while the directorships of dozens of agencies remain vacant).
Again, I’m not saying I want Bernie at the top of the ticket or even necessarily on the ticket at all, but his mental stability is among the least of my concerns.
