Folks, I used to play 6-8-10 hours a day every day until my wrists eventually collapsed and I can assure you that he can play
any of his song, standing or seated, it's just his own decision to drop some of them, unfortunately the best ones
Some of the errors that you hear here and there in Speedway for example would be in telegraph or sultans, but not because they are more difficult than speedway, it's just his own decision
He makes more or less the same errors than Gilmour made at the same age of about 70 in the last tour (2015-2016) and considering that Dire Straits songs have always been much faster than Pink Floyd ones I think MK has aged even better than David.
The walking issue seems to me 'only' a mechanical/orthopedic issue aggravating by being too fat in this tour, I don't see anything too concerning