Doesn't it seem, however, that the only reason Chevy Chase isn't funny anymore is because he lived long enough to "jump the shark". We will never know if, given the time, Belushi would have ended up the very same way.
Does his brother ever talk about him to the press? He wasn't quoted in the article.
I think Chase stopped being funny because somewhere along the way (probably during the various rehabs he had to go through) he got mean and nasty. His humor always had an abusive edge to it but the edge has taken over. The comedy central roast of him was the most viscious affair I've ever seen, he's alienated all his friends and doesn't care. Belushi's humor source was kinder I doubt he'd have gone the Chase route, he still might have lost his ability to be funny (funnier guys than him have lost their touch), but we'd at least be hoping his next project returned to form, as opposed to Chase where we mostly hope there is no next project.
I think Belushi was in the process of jumping the shark. Animal House was his pinnacle. Blues Brothers was okay. Most of the rest were very forgettable. The drugs probably had a lot to do with it, and he had gained around fifty pounds shortly before his death. He was working on a script for some kind of romantic comedy when he died, and according to all accounts was totally butchering it.