But the 45-year-old mother of three is using her influence on new projects, working on a new album due out in October and co-producing the show of a fellow French Canadian songstress setting up shop across the street at Bally's.
"I'm not looking to make friends in the business because I want to do my job, I want to have a good time and go home to my family," Dion said in a recent interview with The Associated Press, sitting on stage next to a protege with whom she casually chatted in French. "But Veronic - it's a different scenario. I'm not quite sure why. I want her to be my friend. I love her. I respect her very, very much."
Veronic DiCaire - a winsome blonde from Ontario with boundless energy and just a wisp of an accent - previously opened for Dion during a 2008 tour stop in Montreal. In late June, she launched a two-month run of "Veronic Voices," in which she impersonates 50 female artists ranging from Whitney Houston to Carrie Underwood and Lady Gaga.
In a city where it's hard to stroll the sidewalk without running into a Michael Jackson or Elvis impressionist, DiCaire's struggle will be rising above the stigmatized title of impersonator - something Dion said DiCaire can do because she "becomes" her characters.
"You've seen impersonators, you've seen men doing women, and women doing men," Dion said. "Sometimes it's funny, and sometimes it's so exaggerated. We've seen it all. With Veronic it's very, very different."
DiCaire has a devoted French-speaking following after living in France, but her Vegas show is her breakout into the Anglophone world. Between summoning the big voice of Amy Winehouse, mimicking the snappy stage gestures of her patroness Dion, and overdoing a Taylor Swift twang, she takes on a wide-eyed, country-girl-meets-big-city persona, at one point offering the self-deprecating quip "pardon my French" when she stumbled over her words.
If the show doesn't take off, it won't be for lack of a mentor. Dion wrote the textbook on creating a Vegas brand, filling up her 4,000-seat auditorium since she initially debuted there in 2003 and disproving doubters who wrote Sin City off as a retirement community for fading stars.
"Critics said, 'Oh, my God, the Titanic's going to sink again, she's going to finish her career here,'" Dion recalled. "We took a chance. It worked really well for us.
"I don't have to be here. The reason why I'm here is because I'm really enjoying being here," she added.
The Vegas appeal, Dion said, is skipping the exhausting tour schedule and going home every night to her producer husband and three boys: 12-year-old Rene Charles and twin 2-year-olds Eddy and Nelson.
The youngest ones are named after heroes - Eddy for French lyricist Eddy Marnay, whom Dion describes as her dad in show business, and Nelson for Nelson Mandela the ailing, 94-year-old former president of South Africa.
"We met with Mr. Mandela. It was a very amazing, privileged moment," she said of the man credited with helping end apartheid. "We both thought it's a hero name ... Nelson Mandela was representing something so positive and so grand."
Apart from duties as mom and mentor, Dion plans to release her first English album in six years this fall. Challenged to keep things fresh after three decades of recording, she said, it includes some unexpected collaborations, including one with R&B artist Ne-Yo.
"The producers and the songwriters kind of proposed, again, amazing songs to me, and I got excited again," she said. "The whole project was extraordinary."