If total public/staff/student sales end up around 45,000 or so (that would seem to be the high end at this point), exactly how many games do you think the paid attendance will crack 60,000? Maybe for the first night game (assuming we don't crap the bed against ISU the week before), but that's about it.
You're certainly not going to find a significant amount of people that want to see any of the other games (Illinois State? Purdue? Maryland?) that don't already have season tickets that are going to purchase singles to this awful schedule.
We will find out in three weeks. What I'm seeing is that there were an average of 67,512 last year. It appears that they are ~7,700 behind, as of last week. If you go by just those two numbers, comparatively, today's numbers project ~60,000.
You asked how many will crack 60? I believe all of them will. People don't want to see Illinois State, I agree (In fact, many posters on here want to see Ill. St. win, but they want to do it from home so they can post on here throughout about how giddy they are), but fans want to see Iowa, and this is their first opportunity to do so. 66,800 showed up to see UNI last year, it wasn't all UNI fans. 64,000 showed up to see Ball State. Pittsburgh will sell well because it is a night game.
But, like I said, only a few weeks now. I'll let you know how it looks from the stands.