Disagreed since the odds of an average, healthy 55-year-old dying in office are less than an 86-year-old simply based upon actuarial tables.
We agree that the next term with an older president will have a greater chance of dying than a younger president would have. I just doubt that it is "probable", but it is "very possible." We have a 99 year old former President, and I do not see any reason why we cannot have an 86 year old former President in 2029.
That said, all the RWers whining about Biden's age are quick to dismiss the obese current 77-year-old they are hoping to elect into office next year.
Biden has 7.25 more years (on average) left, and only needs 5 of them. In other words, he has a greater than even chance of making it... And that is just assuming he gets average healthcare, which we all know he will get better than average healthcare.