hero/villain claim: So it's a tautology if you interpret it like this: You are currently A. You will die. If you don't die as A, you will die as !A. But it's not a tautology because there's an intermediate state between hero and villain that is neither A nor !A.

cancer claim: Again, it sounds like a tautology, but you aren't considering statistics. Sure, if nothing else kills you, you die of exploding fingernails. But the intent of that expression is to say that cancer is the default, it's not a bullet you can dodge forever. I'm not sure I agree, because "old age" != "cancer", but that's what it means.

Or was your question purely rhetorical? I tried...