I think the important thing here, is the fact that newspapers themselves are a dying medium. The cartoons are a tiny part of the newspaper that they included to broaden a newspapers appeal, back in the days when newspapers were big bussiness.
Webcomics, are of course the way forward. For every syndicated comic, there are a thousand published for free on the web. This isnt good for making money, but its good for artistic expression. Sure, theres loads of crap, but there are gems too.
Paper comic books are a waning art form too i think, destroyed by the "comic book guy" stereotype, as satirised on the simpsons. Paper comic books have always been seen as a thing for children and nerds, and what self respecting modern nerd buys a physical version of something he can get for free on the internet?
Paper just isnt cool anymore.