Written by Lola Ogunnaike Yara Shahidi: ‘My Metric for Success Is Having an Impact on Something Greater Than Myself.’ Meghan Markle is a fan. Michelle Obama wrote one of her college recommendation letters. Oprah Winfrey believes she’ll be president of the United States one day. Karey Burke, president of ABC Entertainment, tells me, only half-jokingly, “I want to be her when I grow up.” They’re…