The only way to close the gap would by NY6 type bowl revenue. But as a member of the MWC, we would have to split that with all members of the conference. In that scenario, BYU would have to make a NY6 quite often to make it match. I havne't run the numbers, but have a hard time believing the $$ from MWC membership and a few NY6 bowls a decade would be more than what we have now.
Also, if we just manage to make 2 or 3 NY6 bowls a decade as an independent, there is NO WAY the MWC would make financial sense, even if we did NY6 every year in the MWC, due to the distribution of bowl revenue to the other schools. The $$ from NY6 bowls as an independent would be too big for anything other than P5 membership to make sense for.