They've been touring every year since 2012 doing about 15 shows a year. This would be a viable approach for U2 as they enter their 60s.
I think the Stones do it for the glory and because they get handsomely paid for it.
I think if u2 knocked trying to make albums on the head and just focused on playing shows it wouldn't be the worst idea.
Stones pretty much finished making new music with 05's A Bigger Bang and at that time Jagger was about 60. Bono is coming up to 60 - of course Mick and co made a lot more music in their careers than Bono and co did, but i suppose that was a lot to do with them being in their pomps in different eras.....
The career arcs of making new music but with ever diminishing returns until aged about 60 then taking their carefully crafted live shows out a few times a year could well be similar.