The problem with that is that at YC there is a huge incentive to succeed. Only people which are very passionate about their idea/entrepreneurship are accepted. Furthermore, when you're out of university, a startup is your only hope, and if you fail you have failed, whereas in a class people will be less motivated to succeed, because this is just a single class, and you have your schooling to fall back on.

Finally, the biggest value of YC is the incredible quality of mentors and peers. Naturally, both of those would suffer. Really, this is less a YC class and more a simple startup class, which many universities are doing, but to much less success than YC