When Celine Dion performs the final show of her second residency at the Colosseum at Caesars Palace on June 8, it will mark the end of an era in Las Vegas entertainment. Dion debuted as a Strip headliner more than 15 years ago when, even though its nightlife was booming, Las Vegas was widely considered the place where entertainers went to become nostalgia acts, or the last career chapter before retirement. Dion almost single-handedly changed that perception, opening floodgates that Bette Midler, Elton John, Cher and Rod Stewart would pass through, among many others.

She also demonstrated the benefits of staying put in one venue for an extended engagement as opposed to the rigors of tour travel, which performers from Gwen Stefani to Van Morrison have now picked up on. Mariah Carey and Jennifer Lopez breathed new life into their careers through headliner productions, and no would accuse Lady Gaga, whose Enigma residency at Park MGM debuted Dec. 28, of being close to retirement. Without Dion taking a bold risk and infusing credibility into having Vegas headliner status, things may have turned out vastly different.

Dion may have symbolically given her endorsement to Lady Gaga as the next grand diva of Las Vegas when she attended Gaga’s show on Dec. 30 after performing the first weekend of the final run of Céline, and conspicuously danced her ass off like the ultimate superfan. Gaga reciprocated with a shout-out to the 50-year-old Canadian chanteuse.

“She prayed with me and my entire crew before the show,” said an astonished-sounding Gaga while sitting at her piano. “That is how amazing she is. And when she was asked if she had any advice for me in Las Vegas, she said that I didn’t need it, that I was strong and I knew what I was doing. And I swear to you, oh my God, the number of women that I can count on one hand that are supportive in this industry; it’s like I would lose fingers. You are amazing!”

She then dedicated “You and I” to Dion, who jammed on air guitar during the song before demonstrating her mastery of the choreography to “Bad Romance.” Dion’s unbridled enthusiasm for the next generation is characteristic of her authentic presence, whether onstage or in interviews. She was raised to be a star performer and acts like it, but there’s nothing disingenuous or superficial about her. She is what she is, an embodiment of how optimism and perseverance pays off in the end, and how being yourself in the face of a cynical entertainment press will only increase the devotion of fans.

Dion paid back the shout-out via Instagram: “I had so much fun last night @ladygaga! Your energy on stage is contagious and you literally took my breath away! I wish you all the best with your #Vegas residency!” Respect paid, the amazing Celine Dion turned to preparing for her final New Year’s Eve engagement as a Strip headliner. And don’t be surprised if you see Gaga in the audience at Dion’s final show.

Caesars Palace, 7:30 p.m. Jan. 15-16 & 19-20, $55-$500 plus tax and fee. 866.320.9763