Aside from the student section, the games were pretty well attended. Presumably, the students who got bored and stopped showing up will not renew season tickets for next year. Those students who get tickets for next season will probably be the ones more inclined to attend. All you have to do is compare TCF stadium with the tomb that the Dome was to see the difference.
I think the stadium in general will be better attended by more loyal fans as the years pass.
How many season tickets were bought to get into the "new" stadium in town. How many students bought tickets just to make the opener, etc. Serious football fans that will be graduating students will hopefully have a chance to buy regular tickets next year, incoming freshmen will add bodies to the student section replacing some of the students that were just in it for the opener/warm games/whatever. It will be a process, but the stadium will breathe new life into the fanbase, true sellouts will become more the rule than the exception as the dome crowd and bluehairs get filtered out.