I think John Bonham would’ve been the one to demand a break from the long tours, and being a way from his growing family. Robert was all in as long as John was there, yeah he did say that by 77’ tour they were grinding through the shows but the huge audience going berserk would motivate anyone to continue even if they weren’t in best form in all their shows.( I think a bad Zeppelin show would still be better than a good show from anyone else. )
I guess Robert and John Bonham would have made it clear that Zeppelin was going to stay closer to home, shorter tours, longer breaks, then call it a day by 1995.