I'm in the same boat. I grew up whitetail hunting every weekend of the season with my dad and grandpa in Georgia starting at about age 12. I'm 29 now and grandpa turns 90 between now and 2nd rifle. The three of us have been hunting elk together since 2013 and I moved to Colorado in 2016, so our elk trip and a few days around Christmas are our only opportunities to reunite the three-generations gang and hit the woods.
He's been forgetful and speculative that it was coming for years, but grandpa was officially diagnosed with Alzheimer's just before our 2020 hunt. I think the diagnosis was a curse...when he forgot something he used to stammer and stutter and rack his brain until eventually it came out. Now every time he can't remember some private's name from 'Nam back in '68 he just goes "this damn Alzheimer's I tell ya" and moves along. But that is beside the point.
For some background, he is still totally self sufficient, and otherwise healthy. He has a handful of daily prescription meds but not a fraction of what most of his peers take. He has lived by himself since 2013 when my grandmother passed away. He buys his own groceries and takes care of the house and yard. He takes himself to all his doctor's appointments and makes a daily visit to the local Site One to ruffle the guys' feathers, they're old friends. He and dad still hunt whitetails every Saturday and Sunday of the season, and since 2015 he's gone to Alaska every September pursuing moose with an old Army buddy who owns property there.
That said, without discussing it, I think we all recognize that this year is probably his last elk hunt. Knowing this is making the whole trip bittersweet and I bounce back and forth between having a hard time getting excited for one last hurrah, and making the most of our final outing. While it does feel like taking the dog to the park one last time in some ways, what can you do but cherish it and make the most of it?
I do not question at all his ability to safely handle a rifle, properly identify game animals and other hunters, and make a safe and accurate shot if the opportunity presents itself. He's always self-aware and knows where he is, what he's doing, and why he's there.
I do worry that if he's left alone, he may not be able to find his way back. He still drives, likely not for much longer, as he knows how to get around in a "turn-by-turn" sort of way. He can get to dad's house, but not tell you how to get there on command. Street names come and go with his "good days" and "bad days", but he always knows you turn left at the railroad tracks.
We each carry our cell phone and a two-way radio for communication, and I plan to keep eyes on him at all times this year, even if from afar. He also has an ancient Garmin unit that was meant to save a waypoint, then guide you back to it later, which I intend to set up for him daily with the waypoint being either camp or the truck, whichever is closer to him.
Guess I haven't done much but tell a story here, but man this is a shit situation all around so I thought I'd share my version of it. It sucks having to take the gun from the hands that taught you. I think all we can do as sportsmen is make the moral/ethical decision, and do our best to carry on the legacy of those who passed it on to us.