That basketball run does pay out $10m to MWC, even though it isn't generally how schools are valued. Certainly doesn't hurt in terms of making other conferences interested though. From the article below, it looks like B12 may be a fallback for SDSU if PAC doesn't work out.
A lot of the value comes down to "markets", and both SDSU and SMU are seen as giving eyeballs in desirable media markets.
It is rumored SDSU/SMU were part of the package being marketed for PACs new media deal. The media companies want to know what they are buying. If PAC can continue to get $30m average per team in the media deal, then thats what they'll pay.
Some schools may be worth $50m to the media, and others worth $10m, but generally conferences pay all schools the same.
AAC is one exception I am aware of, they gave $7m/year to legacy members, and only $2m to new members.
Boise St also has a special exception I believe that allows them to have their own media deal. But this is not the norm.
For the PAC, there are rumors they may only see $20m/team this time, which could trigger more chaos.
Another way of looking at this: maybe SDSU was being "underpaid" at 4m/year in MWC, and their media market is worth far more as part of a PAC media deal. That tends to drive conference movement by teams. We'll likely find out whenever the PAC deal is announced. I suspect the departure of SDSU from MWC would negatively impact MWC's media deal somewhat in the future. The same is true for PAC with USC and UCLA departing.
Media deals and money drive everything in FBS, and particularly in the P5.