Since “Keeping Up With the Kardashians” premiered in 2007, the reality show has been a ratings-generating, attention-grabbing stalwart for NBCUniversal’s E! “If you’re the Kardashians, you realize your audience is watching less and less TV every day.” Television End of an era: ‘Keeping Up With the Kardashians’ will stop in 2021 “Keeping Up With the Kardashians” stars Kim Kardashian, Kris …