Josh has said that Illinois' position on NIL cannibalizing from DIA contributions is that NIL will lead to better teams, better teams will lead to more $$ to DIA. Hopefully the positive effects of the latter will outweigh any negatives of the former.
For every team that wins more due to NIL, there will be another team that loses more. It's not like everyone can get better. That said, I do think we're particularly well-positioned in this new environment with a large, relatively wealthy alumni base, really good coaches in both revenue sports, and a really strong AD with a legal background to boot. However things shake out over the next 10 to 15 years, I expect Illinois basketball and football results to be significantly better than they have been in recent memory.