What other legitimate (classic) munis could host a USGA event or PGA tour event if rebuilt.
Assuming a candidate qualifies if currently a muni, even though it historically was a private club . . . the course most likely to host a major championship if restored is Timber Point, East Islip, New York (assuming there is room for enough length). Once the playground for summering gentry that eventually preferred the Hamptons to the Great South Bay this Golden Era masterpiece is well chronicled in Missing Links. In addition, Dr. Bill Quirin discusses a bit of Timber Point's history:
"After organizing is July of 1923, the founders [including Horace Havemeyer] hired Colt & Alison to design an 18-hole golf course. It was nearly two years before the project was completed, because it took a year to dredge up enough sand to fill in the marshland and reclaim 100 acres from Great South Bay. The result was a magnificent test of golf among the sand dunes. It quickly took its place among the country's finest courses . . .. The first nine at Timber Point played through forests of pines, with several holes reminiscent of Pine Valley." Golf Clubs of the MGA pgs. 301-02.
The back nine hugged the Great South Bay, with its most recognized hole named Gibralter, an uphill long 3 par playing into the prevailing wind off the Bay it is a horizon green and great 3.5 par. I grew up playing Timber Point after Suffolk County purchased the property from a struggling membership and a third nine holes was stuffed into the original 18, destroying 6 original holes.
It turns out my great uncle was a member of one of Timber Point's last memberships, that varied over time, and I only wish I had been born to see that original 18.
There's still some great golf holes out there, but poor conditioning and green speeds like shag carpet leave much to the imagination.
This course, if re-stored through what I imagine would be a private-public partnership, could host a US Open if there's enough length out there at the site. I'd say it shouldn't be lengthened too much but without that length a major it couldn't host and without that major, a restoration in could not be since Suffolk County will have to be convinced to lose not only the revenue while the course is shut down but a third of it's volume when 27 holes is returned to 18. I'm sure a share of the concessions would more than make of the County's loss.
This project, however, would be one of the greatest ever undertaken and would be the closest we could get to restoring a course similar in origin and design to the even more famed Lido Club.