I agree she's a bit of a mystery. I think being a global sex symbol who was also a creative force gave her good longevity, and in the last decade+ her random bops have been just in tune enough with the popular music climate (the songs in Spanish, not the English duds) to make her a streaming force too. also being an incredible performer who can tour a lot and put on a show - when you have that voice and that audience you can survive not having a hit or not making great music anymore. probably having a hot mess personal life has also endeared her to people.
I would rank her among the artists I have zero faith in ever to make a great album again though. but it also don't bother.mp3 me that much.