I've been off the air for a bit because my dad is nearing the end of his days. He will certainly never again play No8 for Canterbury or ford the Rakaia up near the glacier and then walk over the Whitcombe Pass. In fact, a week ago he appeared to be "actively dying" (which is apparently a thing) so there has been a clan gathering this last week.
Medical intervention and quality of life become big issues at such times, and paternal responsibilities are
The counterfactual (what would happen without action x?) is critical to weighing these things up, but the facts can easily obscure our understanding of the counterfactual.
We naturally compare the patient to person they previously were, and relative to that counterfactual my dad's physical and cognitive capabilities are much reduced. That's a pretty low hurdle though. Most people over 70 would be in or near that category, and many of them are fine, so "diminished capability" probably isn't the best way to think about this.
I think the right question is whether he wants to keep going or not. In our case, that's not entirely clear because communications are not flash. But its still the right question.