Canine conundrum

My neighbor relies on me to help him take his dog outside for walks but I'll be moving away soon. How can I be of help to him after I leave? I have a neighbor, an elderly mentally disabled man, who inherited a large friendly dog and has been caring for it for a number of years. My neighbor has gradually become too weak to control the dog when coming down the stairs of the stoop of our apartment building, so every evening I help my neighbor take his dog down these stairs. And I understand other people do the same for him in the morning. (I'm certain, though, the poor dog does not get outside often enough.)

I'm moving away soon and won't be able to help my neighbor anymore. In the near term he'll be able to make do - he's able to find someone else to help on evenings I'm not available.

What can I do to help him find a more dependable long-term solution?

It will be difficult to establish, whatever form it takes - my neighbor dislikes change and is easily, frequently distracted. He is consistently (but harmlessly) grumpy.

Could a dog walker help...? I don't know anything about dog walkers. I know my neighbor will resist the idea of someone else walking his dog for him. Is there some simple solution that I'm not thinking of? I do not believe my neighbor has a lot of money.

We're located in lower Manhattan.

Thanks!