The article links to several others. One from 2011 gives a great summary of the number of fans in each school's fan base, fan sharing in major markets, etc. It has lots of numbers and comparison charts. In reference to Independents this link says the following about Notre Dame and BYU:
"Hereâs one of those cliches that turns out to be valid: Notre Dame has a highly nationalized fan base. Its best markets â by the total number of fans, not market share â are New York, Chicago and Boston, each of which rank ahead of its native market of South Bend. It also has decent numbers of fans in markets as far afield as Los Angeles and Washington.
Itâs no wonder, then, that the school has been reluctant to join a conference, which could limit its national exposure.
Brigham Young, as we mentioned, would be an attractive-enough addition for a conference like the Big 12. With about 700,000 fans, it ranks behind 42 automatic-qualifier schools â but ahead of 27 of them."
In 2011, Notre Dame had over 2.2 million fans nationwide - making to fourth behind Ohio State, Michigan, and Penn State. BYU's 710,000 fans nationwide was larger than 3 Big Ten, 3 SEC, 4 ACC, 3 (almost 4) Big 12, and 8 (almost 9) Pac 12 schools - Utah was 10th in the Pac 12 at 352,000 and Oregon was fifth at 628,000.
http://thequad.blogs.nytimes.com/2011/09/19/the-geography-of-college-football-fans-and-realignment-chaos/?_r=0
