The biggest factor for all parties involved with any conference expansion lies with the Assignment of Rights. If I read the article correctly, the Big 12 has the AoR which ends the soonest, and the SEC is the only major conference without one.
If the B1G grabs Oklahoma and Texas, the Big 12 is dead unless they add a lot of CUSA and AAC teams. No one is going to touch anyone from the B1G or the ACC due to $$$ (B1G) and AoR (ACC). PAC 12 is not getting nearly the media $$ they expected out of their TV network but they are basically a regional conference. I don't see a conference plucking anyone from them.
The B1G adding OU and UT renews the OU/Nebraska rivalry. UT's biggest rival was always Texas A&M. Would A&M leave the SEC to : 1) renew the rivalry with UT, 2) make more $$ with BTN, 3) face no AoR penalty, 4) stop getting their arse kicked by Alabama annually? I say the possibility is greater than anyone may think.
If A&M leaves the SEC, does Missouri follow? They get natural rivalries with Illinois and Iowa. Would Arkansas follow suit to quit getting beat up by the SEC, make more money, establish a rivalry with Mizzou and rekindle old SWC (pre-Big 12) rivalries with UT and A&M.
If the SEC starts losing teams, does South Carolina jump to the ACC? ACC could easily absorb West Virginia from the remnants of Big 12. The SEC is then left with their pre-1990 lineup only, which doesn't really hurt them much except they lose the Texas TV footprint.
Big winner: B1G
Winner: ACC
Loser (sort of): SEC
Big loser: Big 12