The next killer smartphone app has arrived — and it offers the potential to transform how we communicate, share knowledge and even make new friends. I am talking about voice-and-audio-based social networking startup Clubhouse. Its platform enables users to drop in and out of ephemeral chat rooms and take part in a range of gatherings, from small "water-cooler" type conversations to larger discussions featuring expert panels, often attended by thousands of listeners. Since its launch last March, Clubhouse has increasingly become a cultural phenomenon, attracting politicians, celebrities and experts from all walks of life. With its success and prominent backing, it may now be poised to upend the entire social media space.