Interestingly Jim Davis stopped doing Garfield ages ago - he just had a team of people doing it on his behalf so he could keep making the money...

Obviously it diminished any legacy Garfield has had but he's still got to go and do what he wanted (Orson's Farm).

But it's not clear that Waterson's something else would ever be commercial or public - just that he was going to go and do something that wasn't Calvin and Hobbes.

Only he will know what his original intention was (or even if he had any sort of clear idea at the time) but he has no children and is presumably financially secure for life from Calvin and Hobbes so at the very least he'll have known that not "working" again was an option.