Discord uses a hashed username system allowing users to have any username they choose, although duplicate names will come with a # number at the end. According to rumors we've received, Xbox may be going the same way.
According to some information I've received over the past few months, Microsoft is working on a broad update to its Xbox Live social systems, with noteworthy changes coming to Xbox Live profiles, and Xbox Live gamertags themselves.
Full story from the WindowsCentral blog...