ESPN dropped out of the B10 media rights because the league wanted $350 million, and would not move to the number off the $300 million they had offered. So those rights went to NBC.
None of that affects the B12, in fact, it may actually help the B12, now that the B10 is out of the picture.
Last year when ESPN held the rights to the B10, they had them one at noon Eastern on ESPN, 3:00 on ABC and then prime time on ABC or ESPN. They still held the rights to the ACC, and the smaller conferences.
Now they have switched from the B10 to the SEC, so the SEC will fill the slots that were before shown on ESPN/ABC.
EPSN still had plenty of slots open for the B12, under the old agreement, why would those slots change now, just because they have SEC? They still need a 3rd conference to fill those slots either the P12 or the B12. That after they have filled all their old slots with SEC teams instead of B10 teams.