Michael’s restaurant, Midtown’s fabled lunch spot for the media elite, celebrates its 30th anniversary on Nov. 6. It’s a grand, well-deserved milestone for restaurateur Michael McCarty’s beloved institution. But the ideal it embodies — power as the main course, with Nicoise salad on the side — isn’t long for the world.

Michael’s is a favorite of so many media and entertainment boldfaces that Post media columnist Keith Kelly regularly mines the house for scoops. Regulars include ABC’s Dan Abrams, CBS’s Maurice DuBois and Lesley Stahl and CNBC’s Andrew Ross Sorkin. In the last few weeks, music mogul Clive Davis, novelist Mary Higgins Clark and Vanity Fair’s Lynn Hirschberg have been in as well.

So much happens there: “Star Wars” creator George Lucas wooed his future wife Mellody Hobson, author Jay McInerney clinched a TV show deal and late Fox News Channel boss Roger Ailes loved to go “just so I can irritate liberals.”

But beyond the white and yellow walls of 24 W. 55th St., New York City’s “power lunch” scene that we once knew and loved is all but over. It wasn’t always as real as nostalgists claim — there were tourists as well as Rockefellers even at the hallowed Four Seasons — but there was substance behind the myth. The afternoon ritual was truly one of the things that made the city special.

That was until Midtown began losing some of its corporate clout to neighborhoods all over town. Condé Nast went to One World Trade Center, Sony to Madison Square Park, HarperCollins to lower Broadway, Time Warner to Columbus Circle (and now Hudson Yards) and ESPN to Pier 17 — a pier! — at the South Street Seaport.

In the early 1990s, restaurateurs and chefs, chased by high Midtown rents, began taking their wares elsewhere, too: to Tribeca, Soho, the Lower East Side. Changing tastes and lifestyles meant that younger executives preferred lighter dishes and mineral water to prime rib and martinis.

Sure, certain places still attract power faces from certain businesses. There are celebrities, lawyers and real estate moguls at Il Gattopardo and at Porter House. Judges, prosecutors and defense attorneys meet and greet at Forlini’s downtown on Baxter Street. Fashionistas and artists blow air-kisses at Balthazar.

But the schmoozing and table-hopping encounters by heavy-hitters who could move markets — the essence of old-school power-lunching at Michael’s or the extinct Four Seasons — is slowly but surely going the way of flip phones.

Suit-and-tie-wearing machers in media and Wall Street gave way to “influencers” — millennials in Untuckit shirts who, when they’re not picking at salads at their desks, crowd communal tables at the bare-bones, gluten- and meat-free Village Den on West 12th Street.

Michael’s is the rare power pit that remains vital, and not only for media boldfaces. Its rear garden room is popular with less-well-known dealmakers in finance and high-end real estate as well.

But the power mystique that still hangs over other celebrated institutions is mostly an illusion. Broadway stars still give interviews at Sardi’s, mainly to play on its old-New York atmosphere. But the curtain long ago came down on the dining-room floor show at Sardi’s, where seemingly wall-to-wall Shuberts, Nederlanders and Barrymores used to talk up every new production. The food’s a lot better today, but not the cast.

I mostly glimpsed power lunching from the wings. It was exciting even from a distance. My late mother-in-law, who was editor-in-chief of the Ladies’ Home Journal, held court in the Four Seasons Pool Room, where I thrilled to the parade of her peers and competitors. My late Post colleague Claudia Cohen introduced me to Le Cirque regulars including her future husband Ronald Perelman.

My producer friend knew everyone at Midtown French glamour spot La Cote Basque. They hilariously thought I was important because he was; a few even invited me to lunch on my own. My New York Post higher-ups gave me too much wine at the Water Club, now a mostly private-event space, where wheelers and dealers sipped their California chardonnay and watched the ships go by.

Power lunching at its peak had a dark side. Eighty percent male and nearly 100 percent white, it defined the elitism of high-end dining day or night. It promoted heavy drinking, smoking and lousy, overpriced food that privileged customers charged to their companies. Ordinary customers at ‘21’ and Le Cirque were exiled to remote Siberias and made to feel like trespassers.

But we’ve lost some precious things as well. The decline of power lunching also accelerated the demise of civilized, comfortable dining rooms with muted sound levels and a taste of history-making in the smoke-filled air.

Face-to-face, human contact made for better decision-making than FaceTime. Wealthy Four Seasons habitues like Jack Rudin and Felix Rohatyn successfully strategized to save the once-crumbling city from ruin over a $40 baked potato. Today’s crowd anywhere is more likely to yak about Kardashian clickbait over microgreens.

The Four Seasons had a mostly sexagerian-and-older crowd before it closed. Michael’s regulars aren’t getting any younger. But for now, let it remind us of the power, and the glory, that was.