In the last few years, i havent seen a single walk on preferred or not make the team. Several were sent to D squad and have come back to try again this fall. Meeting next week on fall reports/status so will know more then. I have seen redshirted (scholarshipped) guy quit after soph fall when performance wasnt where it needed to be and projected outlook was bleak post January, pre-season for playing time. I have seen other guys "not come back" in the last few years as well and i assume they had tough exit meetings post fall and very limited PT during previous season.
College baseball is a business, winning is paramount. Contribute to that or show real promise to do so or you may be on the bubble, regardless of scholarship/status.