I can't stress enough how unheard of it is for a comic strip artist to just walk out on his creation. Usually there are only two possible ends: either the strip gets cancelled when its popularity drops, or the author works on it until they drop dead (happened to Charles Schulz with Peanuts and will probably happen to Jim Davis with Garfield). Some strips are even continued by other artists (https://en.wikipedia.org/wiki/Blondie_(comic_strip)).

Reminds me of R.E.M. (one of my favorite bands) who also decided in 2011 to call it a day and split amicably, thus escaping the fate of all other rock bands who either implode because their members can't stand each other anymore or go on until they, well, drop dead.