The Blizzard controversy has shown us something, irrespective of where you stand on the subject from pure apathy to moral outrage the common thing that can unite people is that the use of a tag rather than a name is not generally offensive or bad.
Many of us already use them, many of them are relatively famous. There however is no real way to provide these across a wide spectrum, we do not actively link our online spheres together nor do we have a central source of identity. The US government has proposed a scheme for identity providers, but the question becomes why do we need or want to pay for these services. As with gravatars we should be able to single source our identities, tying them together as we wish and giving the information to who we specify.
Blizzard and co shouldn't be aiming to create identities for us, but rather allowing us to create identities as we wish. If we need to further sub-domain this, a Blizzard only identity for example then we might consider Blizzard-Identity, or any other kind of identifier we wish, locally we are still Identity however we can also be globally recognised under that system as well.
Free identities for all!