I rather think Vanity Fair, like T&C, is suffering from A) age gap ignorance and B) the formal end of segregation. I mean, the authors of The Preppy Handbook realised there was a problem and did a revision. The last issue of T&C was a desperate - yes desperate - effort to name some Swans, a la CZ.
Anyways, CZ and Jackie O and so forth are not quite ladies who lunch. They were too high profile and traveled too much, esp. to foreign countries. Plus Jackie was Catholic. The ladies who lunch were the lower profile, opera committee grunts. In smaller cities, they had a relative in the ladies who did the church charity coat collection once a year wearing gloves.
There's a bit of difference between 'social clubs' and 'country clubs.' Ladies who lunch is really a social club thing. You see, the club has to be ladies only and close at 4 p.m. Too many night events at these country clubs... Not to mention MEN.
Anyways, the clubs are outmoded, but I'd argue the ladies are still there. WASPs didn't go anywhere. They just became Hipster 2.0's.
P.s. I will argue against Real Housewives being the new ladies who lunch because their husbands don't really the run the world. Melinda Gates would be more like it, except she's a 'horrid liberal'