Ron:
The concept of public courses being used more and more is just getting cranked up. Frankly, the US Open will be a sellout at just about any venue it chooses to go to. However, public courses likely have the greater capacity to sell more tickets.
Ron, a number of years ago the NCAA decided that any final four event would need to hold far more than your traditional b-ball arena. If memory serves, I believe the last one held at a traditional b-ball arena was at the Meadowlands. Bethpage could sell 50,000 tickerts without any issue. I'm siure Erin Hills will do no less. Ditto for Chambers Bay. Merion, on the other hand, will need a shoe-horn to get a max of 15-17,000 people on the grounds.
The SoCal market is also a special one and likely will be re-visisted. Maybe they opt for LACC but I don't see the club changing its outright no answer to hosting it.
Ron, plemty of public side situations will now be more prevalent because of what Bethpage, Erin Hills, Torrey and Chambers Bay have done. The private clubs will be part of the mixture but the bar for $$$ is not with them and the USGA is in a much better position because of the involvement of such clubs to extract that much more in the negotiations.