I like how you quantitatively try to reason that ND + pick your 4 Big 12 schools would not add enough revenue by citing the current contract of NBC / Notre Dame. Your reason being that if Notre Dame itself is only pulling down $10 million per year with NBC and Northwestern, for example, is raking in $22 million due to the Big 10 contract how can the addition of a Nebraska, Kansas, Kansas State and Missouri + Notre Dame not further dilute the existing Big 10 teams revenue streams? The reason: The Roman Catholic Church.
Nearly a quarter of the US population defines itself as Roman Catholic. If the Church itself connects with any one university it would be Notre Dame. There are a hell of a lot of Catholics that would pay the nominal fee asked their cable provider in order to pick up Notre Dame football games on the Big 10 Network. Right now those same people get their milk for free. There are enough Catholics spread throughout the US that identify with Notre Dame football that every single cable operator will eventually need to pay the Big 10 Networks fees to carry the network. That is how getting Notre Dame would pay for itself plus any 4 other schools. In addition to every Catholic college football fan that isn't in the TV footprint of the Big 10 Network you add typical rabid Nebraska fan clamboring to see their team on each Saturday or the fervor that is Kansas basketball and the Big 10 Network can ask a premium on the cable operators.