I personally believe that Philosophy is the place where amateur thinkers reside until a discipline matures and breaks off. Philosophy is thinking without the effort of doing. First it was Physics, Law, Chemistry, Biology, Medicine and we are now seeing Psychology and Sociology departing Philosophy, taking morality and personal identity into the realms of actual science instead of thought experiments. Soon Philosophy will be left with its history and debating the meaning of words. CS and Maths have taken all the interesting logic questions away from Philosophy for example.
I believe what pg advocates at the end has already happened, is always happening to Philosophy. The general truths philosophy helped discover are the sciences, it just that as we get to answering the general truth the philosophers step aside for people who actually do.
Most previously interesting philosophical questions are now interesting scientific questions. There's not much left for philosophers to actually talk about.