It’s the Hadids’ world and we just live in it—for now.

Bella Hadid has landed yet another Vogue, this time appearing veiled on the cover of Vogue Arabia’s September issue, the most important of the fashion magazine calendar. This follows her portrayal on the cover of at least four different editions of Elle magazine in the past six months and is overshadowed only by her elder sister, Gigi, who fronts September’s Korean Vogue after appearing on Arabia’s earlier this year. At 22, the elder daughter of Real Housewife Yolanda Hadid and real estate magnate Mohamed Hadid has already appeared on the cover of 23 different editions of Vogue and will likely overtake record holder Lauren Hutton (26) soon.

The millennial sisters have also turned their mass appeal into cold, hard cash. Gigi was the fifth highest paid model of 2016, taking home $9 million, Forbes reports. This is in large part due to her endorsement contracts with the likes of Reebok, Tommy Hilfiger and Vogue Eyewear. Meanwhile, the 20-year-old Bella has just gotten into the game and recently celebrated a new clothing collaboration with Chrome Hearts.

“They’re leaders in the age of social media modeling,” says Frank Spadafora, chief executive of D’Marie Analytics, a social media research firm. “They’ve evolved into the most desired and industry-respected faces used by fashion houses.”

23 Vogue covers + 2 Teen Vogue + 1 Vogue IT Girl 🙌

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Still, there are nascent signs that we may be reaching peak Hadid. While still among the most popular models in the world, follower growth of the Hadids’ social media accounts now trails those of newer faces like Willow Smith and the more relatable plus size supermodel Ashley Graham, according to data from D’Marie. Per the analytics firm, the value of a post by Gigi across Facebook, Twitter and Instagram is now $251,020, or about $25,000 less than a month ago. Bella’s post value has also dipped to $108,877.45, down almost $3,400 from July. Meanwhile, American Vogue had to issue an apology after pegging a widely-mocked August cover story on Gigi and her musician boyfriend Zayn Malik to gender fluidity, an au courant social issue.

“They won’t last forever,” says pop culture expert Rob Shuter, noting that for many stars “being irrelevant and ignored is a much greater fear than overexposure, so they probably overcompensate and do too much press.”

Still, Shuter doesn’t think the Hadids will accelerate their time in the spotlight from being photographed too much. “You have fifteen minutes of fame so grab as many covers and attention before it goes away.”

The Hadids of course, won’t be the first to fade away. Paris and Nicky Hilton were the celebrity sister pair of the mid aughts, before being replaced by the multi-generational Kardashian-Jenner franchise. Meanwhile Kim Kardashian’s star has been waning—see tanking “Keeping Up With the Karadashians” rankings— at the expense of her half-sister Kylie Jenner, whose makeup brand is set to do $1 billion in sales. And while Taylor Swift has been in the headlines recently for speaking up against sexual assault, she’s cultivating less attention than just three years ago, when she was publicly offering to pay the tuition fees of her fans.

That said, no longer being the most buzzed about personality is not necessarily a bad thing. Just look at Paris Hilton, who has gone on to a highly lucrative post-reality television career that includes playing DJ for reportedly $1 million a gig, making her the best compensated female spinner in the world. The heiress’ fragrance is now sold in 63 countries and has done $3 billion in sales. “The world’s a massive place,” says Shuter. “Paris has fragrances sold in London department stores that aren’t in America. They’ll make money in other ways.”