One of my favourite comic artists, Mads Eriksen [1][2] basically "disappeared" in 2008-2009 and didn't start regularly publishing comics again for more than a decade (at a much slower pace) because of the pressure and burnout.

Maybe Watterson could have squeezed another year or two out of himself, but it's by no means a given it wouldn't have meant unreasonable personal sacrifice.

[1] https://en.wikipedia.org/wiki/Mads_Eriksen_(cartoonist)

[2] https://en.wikipedia.org/wiki/M_(comic_strip)