If ServiceWorkers are coming to Safari for macOS and iOS, it looks like progressive web applications will be pretty plausible across all major modern browsers -- both desktop and mobile. You'll still have a problem with older browsers (and thus older machines that haven't updated), but this can still get you a single codebase across desktop and mobile, which is appealing to a lot of companies. It'll be curious to see how much of an impact this has on React Native traction.