The owner of .ycombinator tld would own the https://ycombinator/ https://ycombinator/ domain. See http://ai/ http://ai/ for example. Nothing stopping you from

The owner of .ycombinator tld would own the https://ycombinator/ https://ycombinator/ domain. See http://ai/ http://ai/ for example. Nothing stopping you from doing this besides the fact that it's kind of expensive and probably not exactly supported.