Family Budget: What could go wrong during the college years?

Well, it had been something in the back of my mind, but this thread made me redo my spreadsheet and assume 5 years at each of the schools DS has been accepted to. He is very strong in math and science, but I am a little worried about his organizational skills and time management combined with his love of gaming going unchecked in college. He may very well surprise me and rock it from the get go, but I wouldn’t be surprised if he struggled for a bit at first and had to learn a few things the hard way. Even though I’m totally anti-loan I’m thinking of having him take out the subsidized loans offered each year the first 4 years, setting it aside and hanging that over his head as being he has to use them to pay for the 5th year if he ends up needing to do that to help motivate him, while still having enough in the budget to pay for 5 years without loans.