Short answer is really fucking down, but I think it is bigger than OU. I think there will be college football before 2021 and college football after 2021. NIL, transfer portal, super conferences, all that is just getting started. It is a tectonic shift for college football.
In 10-20 years, there are going to be a handful of teams capable of recruiting like and amassing the talent like Alabama has in the last 10 years, and they very well may not include not only Oklahoma, but Alabama. Texas has the GDP of Russia, the 10th largest economy in the world. Oklahoma and Alabama has the GDP of Kazakhstan. The alumni base of these flagship state universities can now legally pay football players whatever their business and personal finances allow. Thus, College Football has become a professional league without a salary cap to enforce relative parity. In such a world, a Nick Saban might never stick at Alabama because he could never financially compete with USC, Texas, A&M, etc... for first choice of talent.
This was part of Lincoln Riley's calculus when leaving OU for USC. It was at the root of Saban trashing Jimbo Fisher for "paying players." Few programs will be better positioned than Texas to succeed in this new world. We have large, wealthy alumni base imbued with a college football culture bordering on religion. As does A&M, USC, and some others. Oklahoma, Alabama, they can match the culture, but they aren't going to match the money that can be brought to bear for player talent.
Unless there are some sort of measures put in place to equalize what players can make at universities with disparate alumni economics, there are going to be a lot of new Nebraskas littering the college football landscape.