For a long time I thought that the B1G wouldn't take Notre Dame because their academics aren't good enough. Notre Dame fans think that I'm either stoned or joking when I say that because Notre Dame is a very good undergrad school but I'm neither stoned nor joking. The academics that the B1G cared about were the graduate/research programs and Notre Dame is absolutely pathetic on that front. However, we took Oregon so apparently academics don't matter anymore and it is all about eyeballs.
I think that Notre Dame is a difficult possibility to consider because they aren't like the others. The vast majority of CFB fandom is geographically based. Even when it isn't, it frequently is just with a delay. Ie,
@OrangeAfroMan lives in Arizona and is a Florida fan but he grew up in Florida. I'm sure there are also some second and maybe even third generation fans who root for a team from the state that their Dad or Grandfather grew up in.
Notre Dame is different because, I think, most of their fandom is based on religion rather than geography.
They are also different because, in my experience a LOT of Notre Dame fans either have a second school or Notre Dame IS their second school. I know a slew of Catholic Ohioans who are either ND/tOSU or tOSU/ND fans. I'm sure the same thing exists in other states.
I do think that
@OrangeAfroMan has a point here:
Is ND's fan base going to have a bubble in 10-20 years, in terms of aging out? Morbid, I know, but the golden domers are not special to anyone under the age of 35. Their privileged status probably seems really odd to most, actually.
I don't know that it is necessarily as short as 10-20 years but I do think that it is probably in long-term decline. The growth markets to look at are Arizona, Virginia, North Carolina, Georgia, Florida, etc.