There's no need to replace anything. Nobody[1] uses domain names any more to browse the web. That's what Google, the default browser home page, and the omni-bar is for. I don't know a single non-web-developer who uses domain names. Everybody just drops "facebook" or "google"(?!) in the search box that shows up when the browser opens.
1. Well, nobody except for a rounding error number of people who hang out in places like HN.