It’s 8:30 p.m. in Paris, and Celine Dion is late. In her absence, two giant monoliths tower over the audience. They are parted down the middle, like gates to another world. “That was Oprah Winfrey,” said a British man in the row behind us. “Walking down there. And Michelle Obama is here.” “Where?” Snapped a French journalist, who has already announced she is covering Dion’s debut performance in a month-long run. “Tell me if you see anyone else.” There are plenty of people to see — close to 45,000, in fact — and their combined energy is frenetic. Since there is no opening act, a hopeful ‘CE-LINE’ chant sounds at the end of every upbeat song…