Your scenario, RR, will not happen anytime soon. The MWC recently looked at the expansion issue, and chose only to add TCU. That only complicated C-USA's pick for a #12 replacement, which according to reports, will be resolved by adding UTEP.
Ironically, C-USA has been the conference most changed by all the recent conference expansion/switches that were initiated last year by the ACC raid on the BE. Yet, C-USA while becoming more southern, may have helped itself for the long term in all-sports identity. It all involves a shifting of basically second tier 1-A schools, acknowleging there is a mythical third tier (some SunBelt entities, etc.). Fundamentally, only the ACC absorbed real prominent ones.
If the MWC, indeed went to 12 with 3 WAC additions, that does not mean they would be totally secure in the changing conference landscape. What if the PAC 10 in the future decided to add two? Guess where they may come from? Suppose there was a change in the Big 12 in the future, Colorado State may get targeted.
The MWC, as a whole, may be viewed to be better than the WAC. But it is neither profound nor comprehensive.
A group of the BE (UCONN, WVU, Rutgers, Pitt) viewed the ACC and Miami were out to destroy the BE. Rather, it may be more of the ACC being opportunistic at the expense of the BE. By comparison, it does not seem the MWC views the WAC as a regional threat, and thus take a few members from them in order to destroy them.
Having the WAC in the west, may be supportive to college football/sports in general, rather than a detractor.
The MWC was born out of the WAC. Their intent is not to re-consolidate. Some conferences just have not embraced "12" as the magic number. Of course that can change, but the Big 10, PAC 10, and BE are not doing it anytime soon.
SEC territory involves much of the SunBelt, C-USA, a quarter of the ACC, and tidbits of the revamped BE. I doubt the SEC feels its future is threatened by any of it. Thus, the vast American far west, can handle three (PAC 10, MWC, & WAC) 1-A conferences just fine. This does not mean losing UTEP will not hurt the WAC. And, the LA Tech distance factor is a troubling matter that warrants some strategic thinking.