You mean the author died and he did leave details on how the story is supposed to end (you'll see in the artist for the novels, THORES Shibamoto's, artbook. His close friend supposed to finish it for him though.
The manga-ka is all alive (in fact, she did the first ED of Zoku Sayonara Zetsubou-sensei's designs).
The mango is so much superior though. It flows a lot nicer and there's more action.