Interesting. To the people who have visited and went to ND. In your opinion, could the surrounding facilities, hotels, restaurants, and bars of South Bend support say another fifteen thousand fans?
There was an article I think in the South Bend Tribune a couple of years ago when the latest round of stadium expansions took place. The stadium can be expanded if the Administration choses to. Parking is an issue but could be accommodated through a combination of approaches. Traffic is an issue. But the biggest problem is hotels and restaurants. The article cited various studies, planning agencies, and licensing data. The people that own existing faciilites aren't going to expand to handle 20K people for 6 or 7 dates or weekends. What do they do with the facilities the rest of the year? Same point pertains to new facilities.
Two other factors influence future expansion, Student Body Size and Large National fan base (alumni and subway).
ND has a small student body. Check the number of students at UM, OSU, etc. Far easier to fill a 100K stadium with a 40K student body that already have rooms and eating facilities.
ND's fan base is national. Fans that attend games at most colleges generally live within the state and drive to games. They don't need a lot of hotel rooms. They may or may not need visit a resaurant but they don't need them for the full weekend. ND has a higher percentage of fans that travel far distances, CA, TX, FL, MA. That's also one of the reason ND's fan base travels well to away games, neutral sites, and bowl games. They're accustomed to it for home games.