There will still be NIL along with rev share. Vandy COULD decide to overspend there. And if they do, they can outspend Tennessee, Alabama, Florida, Georgia, etc.
But as you allude, they have a history of abstaining from putting their vast resources into athletics. The one exception was baseball, when everyone was capped at 11.7, but Vanderbilt was fielding a roster of 35 fully funded scholarships because they were willing to put money into an endowment for those extra scholarships. The result was a dominant baseball program, until NIL evened the playing field.
We'll see if Vandy decides to spend big. But they can if they want to.