In theory, the Alliance could decline to pay salaries, which the SEC would pay. As you wrote, that would lead to separate Alliance and SEC ecosystems and playoffs. The SEC would destroy or greatly reduce its non-revenue sports to fund paying players. The alliance would continue to not pay players to continue to spin off revenue to fund non-revenue sports.

If the Alliance did that, would lesser conferences surpass it because of their willingness to pay players and sacrifice non-revenue sports?

My guess is alliance schools will pay players and will fund non-revenue sports through student assessments and non-– athletic department funds.