If you think about it, what really was the point of .com, .net, .org etc... Does it really make sense that you can have both twitter.com and twitter.net? In both cases, you recognize "twitter" as the name, with .com and .net as fodder. And considering that twitter does not own twitter.net shows how meaningless that .net domain is.
So you currently have twitter.com/yourname, when it could be just yourname.twitter. Or yourname.facebook. And instead of yourname@gmail.com, it would just be yourname@gmail. blahblah@hotmail. whosit@yahoo. mikeymike@doodad. stevejobs@apple. pg@yc.
Furthermore, the ".com" has always been a blemish to branding. You have this beautiful simple brand name (Nike, Apple, Cisco) but then you have to advertise the url (nike.com, apple.com, cisco.com), both decapping your name and sticking the .com on the end.
I know this whole .com, .net, .org, .ly has been ingrained into our structure and psyche, but just consider the above to see how much simpler it could be.