I'm sure you know the house proposal is pretty much dead on arrival in the Senate anyway, they can only have one more defection. However, for the sake of conversation let's assume it's absolutely going to happen. I do agree with you that there will be some attempt at a work around for the universities, an attempt at finding a loophole, that's pretty much how accountants are doing these things anyway. I do think that the effect wouldn't be as bad as you may think. I'm going to assume that most of the seats that have a donation attached to them are going to people who still get the standard deduction, especially given the standard deduction is purported to be increasing. I know where I sit and what I pay for a donation per seat, my seats aren't the best but they're better than most. Despite paying a decent contribution for four seats I still hit the standard deduction, I figure most at my donor level and below are in the same boat.
Now this is a completely different story for sections 4-6 and premium seating. I do think that people in these sections love their school and college football enough where they can afford to keep the premium seats without the tax credit. I think the biggest effect will be on the brokers who purchase these season tickets to attempt to turn a profit, I can't see them ponying up for that without the credit. So in the end it may actually help the consumer.