He is the hero of the story, sure, but he has legit murdered people, and ordered people to be murdered. And let's not forget he is making METH, one of the hands down worst hard drugs you could do. Walt himself said without him, a business large enough to be on the NASDAQ would go under instantly. I like this story because it shows the changes this family man has gone through due to the circumstances he was put through, but it shows the dark side of it all. Not because it is following the life of this 'hero' who is put on a pedestal or anything.
That's why I think he will not die of cancer. Because the point of this show should not be to glorify his lifestyle choices, but instead to show that, as someone said, Breaking Bad only gives you problems. The sweetest ending for this whole thing would be for him to be completely cured of his cancer and for his decisions to lead to his death. It's predictable, sure. But it's poetic and would mean way more than any other ending, IMO.