Nobody is watching any MW schools play other than MW fans. If you add schools you add more MW fans. Folks like to watch their own 5th best regional school play on tv, too even if said schools don't draw a lot of other viewers. The MW is not competing against any other conference for tv viewers. They lose in that regard every time. Take a look at the tv deal they have. Tiny tiny tiny. There is a reason for that.
The ideal size for the MW is 9 schools. The reason they have 12 is because it adds more time zone inventory. Without the time zone inventory the conference probably does not have tv deal with a national provider.
At any rate, it does not appear that the MW has any interest in adding schools from anywhere unless they have to to maintain an 8 game football schedule.