IDK what you mean by good faith, but I honestly don't think enrollment will drop much if they lose tax exempt status and have to solely raise tuition to cover it. And it won't bankrupt ISU either.
ISU budget is appx $700M, I think that's annual expenses I saw referenced in an article. No idea what their income is, but I doubt it is more (or much more) than that, because the State still sends them cash annually. If ISU was generating lots of positive cash flow, the state surely wouldn't be sending cash.
So how much taxable profit will they show on that? $50M? $100M? Maybe none? They can depreciate a heck of a lot of stuff. Does ISU even turn a profit? But let's say it's $50-100M annual. At a combined tax rate of 25% overall, that's on the order of $1k per student annually. So no, I don't think it will be that big a deal.
That's a quick ROM, and I don't really know anything about ISU's P&L. Probably
@isufbcurt can comment on it more expertly.
PS - the impact of giving/donations might be a bigger problem. You might not get as many millions donated if those donations are not tax deductions. No idea where to begin scaling that problem.