If this was pre-NIL, the marginal value of these media dollars to football and MBB would be pretty small. Pretty much every power conference team has good enough facilities and services to student-athletes that it was having a small impact on recruiting and thus on the field performance. BIG has had a massive media dollar advantage over the Big 12 for 15 years and it never materialized to on the field/court superiority.AD's are restricted by the NCAA in using funds for NIL deals. Since most of these are public institutions, it wouldn't be that hard to prove if it were happening either.
But to your point, what are they going to do with this money? I feel like its at the point where all these schools already have new and shiny stuff. I guess they could pay coaches and administrative more. The SEC will probably do locker room renovations every couple years now (it already seems like they are).
Post-NIL, these media dollars become much more valuable as donors that used to dump big money into ADs now likely divert at least some to pay for play.
If it was pre-NIL, I think you would've seen a big boost to the money losing sports (basically everything but MBB and FB). They will still probably see some, but you might see ADs hoarding some cash in anticipation of donor diversions to pay for play.