Rhetorical question, I assume.
No, NIL didn't kill the upset, but it certainly put it on life support. Minor upsets might still occur, but i don't see the odds of anything crazier than a 10 knocking off a 7 happening. What's worse is if an 11 topples a 6, and the star player on the 11 has another year of school left, he'll likely be offered a big bag of cash to abandon his former team.
Barring injuries I don't see another Fairleigh Dickenson knocking off Purdue or St. Peter's 2022 team making the elite 8 as even a remote possibility, and it'll just get worse as the rich get richer and the poor get poorer.