Fun prompt.
In the broad sweep of history so long as the framework was conferences negotiating individual TV deals, consolidation was inevitable. The timeline might change, which schools in which conferences might change, but competing for those TV dollars meant destruction of the system eventually. The only way to prevent us getting here was collectivization in some form, which would have had the added advantage of leveraging quasi-monopoly power against the broadcasters. That's the happy version of the story and at every step since the Supreme Court handed schools and conferences TV rights, that SHOULD have been the decision.
As to what could have really changed the way it all went down, I think there are better moments to point at.
The first I said above, if CBS extends with the SEC for their first-tier games in 2019, that drastically reduces the incentive for ESPN and the SEC to coax Texas and Oklahoma, and also probably ensures ESPN's participation in the next Big Ten deal. That kicks the Power Five system to 2030 at least, into a new media paradigm we can't yet see. Who knows what comes out the other side of that hypothetical.
And then the second one is Nebraska, a move the Big Ten made in order to get to 12, which the NCAA mandated to allow for a football championship game, a rule they have since loosened. If we'd been allowed to hold a title game under current rules, we don't make that move, and without destabilization of the Big XII, the five conferences stay on much more equal power footing through the 2010's, a more durable equilibrium (as unhappy of a family as the Big 12 always was notwithstanding.)
(We also have to assume that the Pac 16 doesn't happen, which was a whisker away, only prevented by a financially senseless last-minute ESPN bribe of Texas. If the Pac 16 happens in June 2010, we have a 4X16 conference system by July 2010. That's the biggest contingency in the bunch.)
But what really should have happened, from a Big Ten perspective? When the BTN launch was so successful, and suddenly gave the league this huge platform in the homes of everyone in the Midwest, the league should have taken a long term view, invested, and tried to fill that platform, make it valuable. Most obvious there would have been pushing to make new revenue sports of properties that are known winners on TV, baseball and hockey. It needn't have necessarily been strictly sports though, something like the Big 10K in Chicago, not a TV property, but it showed the path of the Big Ten as a Midwestern lifestyle brand, something that could engage people in a deeper and more sustained way. It might not have worked, it might not have aged all that well in the era of media fragmentation (to say nothing of political culture war), but in 2007 that path was there and part of the discussion.
That was pursued barely at all, no sincere investment along those lines was ever done. The BTN has been a theft of $1 per month from it's inception, always with terrible ratings, the cheapest possible programming, and not the slightest attempt to make it worth more to the consumer than the old ESPN+ syndication system was. Just a cynical ploy for dollars, and a wildly successful one, the story of Jim Delany's career.
It's possible that the college sports world could have shaken out where something like "Ohio State and Penn State to the SEC" could have entered the conversation. Never likely, but if we'd stood pat at 11 (or 10) while others started eating each other, that's a possible future. But if the conference had attacked the opportunity to make Big Ten membership something deeper and more comprehensive (making it among other things more lucrative with diversified revenue streams), that could have made leaving unthinkable in a way more meaningful than just "no better TV deal from now to 2031 is available".