Who's walking who?

I am the kind of person who generally accepts the imperfections of life.
From the day we brought baby B home I attempted to have him walk at my side instead of out in front.
All attempts, using every known training method (well humane and reasonable ones) failed.
Somewhere after 4 or 5 yrs I gave up.
He walks out in front, he isn't pulling, but he's out in front.
Many who walk with us love to play a silly game of getting out in front of him, which inspires him to gallop into the lead.

When we do a walk at a large event, he charges to the front. I don't fight it, I plan for it and use my human intelligence to devise a strategy that minimizes the impact on me.

There's an older couple that are new to our neighborhood who have on multiple occasions seen us and shouted, "who is walking who?" and I respond with a smile, "he's my personal trainer, walks me everyday!"

It is never as clear that this is the case as it is on our 5am walks. This morning was foggy but with a full or nearly full moon lighting our way. He was tired and I was as usual half asleep. When he is tired it is easier to see that he totally perceives walking me as one of his jobs.
He waits at the back door while I pick a jacket, grab some tissues, find my spare house key, etc.
Then we go into the garage and he waits for me to put his lighted vest or harness on and stands just outside the side door, back to me, just waiting for me to exit and close up the house.
Once I clip the leash on, he becomes almost robotic. It makes me LOL as he hits his stride and has this, "let's get this job done" attitude.
He's out in front setting a speedy pace, surveying, looking for critters, or a new branch or decoration to be investigated.
He pees, he poops, knows the route so never even glances back to check in with me.
After pooping is done, the trot is constant, no more sniffing, heading home now, out walking my mom.
Once home, he has a drink, and waits for his kibble.
On tired days, he goes right to his bed and is asleep in an instant.

So yes elderly grumpy couple - he walks me everyday. And I am totally fine with it.
I wonder some days, when he's both tired and clearly those banged up old joints aren't working real well, what I'll do when he's gone. Who'll walk me then?