In Las Vegas, where she has a residency at Caesars Palace, she has clocked up more than 1000 shows. When tickets went on sale for her UK tour, which started this week, they sold out within minutes, despite costing upwards of $175 a piece.
And her epic turn at the Billboard awards - during which she appeared from behind a jewelled curtain hanging from an enormous chandelier and wore one of the most preposterous dresses ever to grace a stage - put the night's other performances, by current stars such as Miley Cyrus, to shame. It was, to quote one critic, among "the most memorable Billboard performances in history".
What is going on?
The shift is partly down to Dion herself and partly down to the mysterious way in which popular tastes change. To start with, Dion: the singer, long derided for her earnestness, seems to have stopped taking herself so seriously.
Her behaviour at last month's Met Gala in New York was a case in point: appearing at the annual fashion celebration for the first time, Dion swanned around in Versace, did a tongue-in-cheek photo shoot for Vogue (which involved crawling on the floor and holding her shoe up to her ear like a phone) and then proudly Instagrammed her stop-off on the way home: a common or garden hot dog stand.
While many guests far less famous than Dion spent the night pouting, posing and playing it cool, she was clearly beyond excited to be invited. She showed off more of her personality and humour in one night than she had in her previous 49 years, and, in the process, upstaged younger stars like Rihanna, Katy Perry and professional headline-stealer Kim Kardashian.
"With the Met Gala, you never know if, or when, you'll be invited next," said Vanity Fair writer Erika Harwood. "Celine Dion seemed aware of that and lived her first to the fullest."
This change in attitude has a sad provenance. In January 2016, Dion lost two people who were incredibly close to her: her husband, manager and father of her three sons, Rene Angelil - 25 years her senior and apparently the only man she'd ever kissed - and, just two days later, her brother, Daniel, who had, like Angelil, been battling cancer.
Suddenly, Dion - mocked for singing in multiple languages, derided for her love of yodel-y high notes and regarded as something of a cold fish, since she always, despite the soppiness of her songs, seemed so composed - was human.
"Before he died it was very, very difficult for all of us," she said a few months after Angelil's death. "To see the man of my life die a little bit more every day. And when he left, it was kind of a relief for me."
Those huge, overblown ballads, almost all of them about heartbreak (her biggest hits internationally have been My Heart Will Go On, Think Twice and Because You Loved Me), now felt meaningful. And Dion's decision to carry on performing within a few weeks of becoming a widow felt brave and bold, especially since she wept openly on stage, with no attempts to hide her grief.
In today's world, where people crave authenticity - in everything from politics to pop music - such public displays of emotion matter. Clips of Dion's crying went viral.
The other aspect to Dion that has fans buzzing is the unabashed showiness of her performances. While in the 90s she was normally seen in jeans and crisp, white T-shirts, little black dresses or terrible beige trouser suits, these days Dion wears edgy couture and belts out her hits while being showered with gold confetti, or alongside holograms of Frank Sinatra and Elvis Presley.
It's not just her performances that are fabulously OTT either - the ostentatious Florida mansion she lived in with Angelil has a water park, complete with multiple flumes, in the garden.
What seemed so uncool in the era of WAGs and Eurotrash now feels worth celebrating. In a time when many pop stars go to great pains to show how "normal" they are, the ridiculousness of Dion actually feels more authentic.
After all, if you were the best-selling Canadian artist of all time and the winner of five Grammy awards, wouldn't you consider transforming your home into your own personal Center Parcs? In her own words: "Some people do drugs and go out every weekend. I build a water park."
Perhaps dion's surprising rise to icon status is also part of the natural cycle of the music industry.
The young pop stars of 2017 grew up with their mums listening to Dion's ballads. Her hits are talent show favourites. These singers don't remember that Dion used to be so supremely uncool - to them, she's just as influential as the other artists they heard growing up, such as Whitney Houston and Madonna.
Meanwhile, the cool indie kids of the 90s, who scoffed at Dion's success, are now 30 and 40-somethings, whose social lives consist largely of weddings and occasional office karaoke outings - two environments where the back catalogue of Dion is practically compulsory.
These 90s kids don't care about being cool anymore - perhaps those Radiohead T-shirts were just a front all along for the fact that they were actually weeping in their bedrooms to My Heart Will Go On.
Alan Edwards, founder of PR firm The Outside Organisation, believes Dion's renaissance is largely down to the power of her vocals.
"Young pretenders come and go but Celine Dion has The Voice, and that has been the key to her longevity," he says. "It's still recognisable within seconds in all corners of the globe and it's one which resonates across age groups - even the younger generation who grew up with their parents smooching to her songs."
Many of this generation will be attending Dion's UK gigs at The O2 Arena, in London, and even those who snapped up the tickets semi-ironically will inevitably well up when the big, cheesy ballads start. After that, Dion will resume her record-breaking residency in Las Vegas, the capital of kitsch and the perfect venue for this triumphant, tragic, freshly-crowned icon to spend her time.
"Families of multiple generations are willing to pay top dollar to hear her voice," says Edwards.
"Many grieved with her after the loss of her husband and she has always been a very human star - humble, articulate, witty, smart and with undeniable talent."
