The Book from the PhD?

If I were to write a book on the basis of my PhD what would it be about? Would it be a practical guide into setting up and managing a scholarship programme? (Probably not as that market has been filled). Or would it be something more academic and fundamental questioning the nature of international collaboration in universities and the contexts for understanding them? (In which case for whom would this be written and at what level? Is there not already enough theorising about higher education?).