Philosophy can’t disappear because upon finding an answer, the human mind finds another question. Philosophy is the branch that keeps our brains entertained. It poses unanswerable questions; just in case we decide to slack off and decide we have answered all the questions. It is the human mind’s job to ask questions; it is in our nature and yet we cannot know our own true nature.
And so the mind seems to be inevitably bound to an asymptotic degree of self-comprehension. If philosophy is alive, it is because every branch of knowledge stems from it. And ultimately, I think if it were to die, it would be because we, as a species, lived long enough to see those branches unified in a cohesive, universal theory of knowledge.