This is a wonderful idea, Lucy! I liked how you're taking on some of academia's sacred cows, namely exams and all-inclusive tuition, to create a personalized and more effective approach to higher education. I think a world of Uber, Airbnb and other mega platform plays, this platform you are suggesting to significantly reduce costs for students and give them exactly what they need in their future endeavors is truly disprove.
It looks like this is a work in progress, but some things I wished you covered are 1. Who is the user?, 2. What does success look like? You've made your point that this would be for junior and senior year students, but beyond that what are the characteristics of the kind of student who would benefit the most from PBL? As for success, I'm wondering if a particular number of projects, number of student and faculty participants, discounted PBL rate, or a mix of those would be the ideal outcome for your project.
Finally, I'm curious which and what kind of institutions would be on board with this. I think the potential for partnerships is very promising. Between private and public colleges, four year or community colleges, it's a broad landscape and thinking about the kinds of allies for this and how they would benefit differently would be useful. Perhaps not institutions at large but individual departments are a better way of thinking about stakeholders, since they have more control over student theses and capstone project. I hope you'll consider those for your stakeholder analysis! I'm curious to see how this develops and would love to see this come to life. Good luck!