Possible, but the previous 4 exits occurred prior to the 2012 change in bylaws. The reason the Big12 was willing to negotiate lower buyouts was two-fold.
1. The financial impact on the conference was considerably lower as evidenced by the media partners' willingness to renegotiate a more lucrative contract for the conference.
2. The language in the bylaws was somewhat unclear vis a vis membership and withdrawal. For example, the bylaws called for a reaffirmation of membership every 5 years. This reaffirmation never occurred, giving lawyers the opportunity to call into question the Big12's standing should the dispute end up in litigation.
Neither of those factors are in play now. The Big12 has much more incentive to play hardball and the prior ambiguities in the bylaws no longer exist.
If UT/OU are able to negotiate a reduction in the exit fee, I expect the fee to still be much greater than the approximately $9 million fees paid by CU, NU, and A&M (Mizzou's fee was a bit higher). Given that Big12 distributions are about 3X greater than in 2011, expect the lowest potential settlement to match that factor.