The only aspect of this plan that is appealing is the idea that the USGA would no longer have to modify great courses so that they can host the US Open. Indeed, many courses modified themselves by choice to get a better chance at hosting an Open, but the changes have still been caused indirectly by the USGA.
However, I agree consolidating the USGA championships into one major venue would NOT eliminate the trend of course modification. If anything, it would create a new "Augusta syndrome." Course owners and memberships would be convinced that their courses needed to be up to standard with the USGA championship facility. Since the facility would be owned by the USGA, this would provide an official standard for championship golf that would be more persuasive than the unofficial Augusta standard that exists now. Furthermore, courses would likely make even more radical changes considering that there would be fewer prestigious for which they could compete to host.
Major championships and rankings are likely the two biggest causes of major golf course renovations. However, you would have to eliminate the majors altogether to keep courses from making changes because of them. Overall, this plan proves once again that Peter Kostis does not understand the game of golf.