While is possible that a single identity system will emerge for the Internet, it's not likely. Hence the claim by Microsoft's InfoCard to be a "meatasystem" for identity. That is, an infrastructure that other identities can ride on. Alternately, others are building such a metasystem from the bottom up.
Right now, that effort goes by the unfortunate moniker of YADIS. YADIS is a way of discovering the capabilites of various identity systems. Drummond Reed just announced that YADIS will also include i-names in addition to OpenID and LID.