First, let me state I hope USC gets more than a slap on the wrist for the indiscretions of a former Heisman winner, which seem out of whack in comparison to extra practice time and impermissible coaching. I agree with popular sentiment that appears it's not likely they get much, but my assumptions are based on what the NCAA's dealing with—-namely an uncooperative Bush, no subpoena power, no boosters involved, just douchey start-up agent wannabes, etc.
There's a somewhat popular notion, however, that creeps up in board comments from time to time that NCAA won't come down hard on Southern Cal because the Trojans are some kind of ridiculous revenue generator for the NCAA. Others have made the point here that this idea is more bluster than fact. For what it's worth, here are the numbers:
2009 NCAA revenue was approximately $702 million according to KPMG-audited statements you can peruse here
How that $702 million breaks down roughly:
85% television and marketing rights fees (almost if not entirely from CBS and ESPN for hoops tournament)
1% Sales and services
3% Contribution-facilities/Contribution-other/NIT, LLC/Eligibility Center, LLC/College Football/Arbiter/eOfficials
The punishment (or lack thereof) they end up with very well may seem unfair to the rest of college football, but it I'm guessing it will be a reflection of what the investigation turned up, not dollars.