I feel like it's almost guaranteed they take at least two more MWC teams (and up to four). I also feel like they are hoping something happens to the ACC that puts Stanford and Cal back on the market (short of the ACC imploding, I just don't think there's any way that the "resurrected" PAC12 can get enough TV money to make it worth those two teams to leave). Once it is apparent that they won't get those in the next 6, you are right - they will let the MWC teams fight and bid against each other to see who gets included.
There's probably a scenario where all 8 of the remaining MWC schools agree to just waive the poaching fee and buyout for the four that have already defected in return for letting all 8 of them join to create a "PAC14". It seems to me that whatever "dilution" occurs as a result of letting New Mexico and Wyoming into the league could probably be offset by not having to pay the $80 million + in fees that they are currently set to lay out.