OpenID is getting more attention this week with Yahoo announcing their use of it. It is getting a little late for predictions, but I'll throw out a long term prediction that any true SSO of this magnitude will not come out of the US, but rather Europe.
The US does not have a history of cooperation, but rather captilistic competition. Rather than one "universal" ID, we'll have 5 of them all competing. If Yahoo adopts OpenID, then Microsoft will use their own and Google will use anothe...oh wait, they already do! We have no hope of having any type of "universal" ID coming out of private industry in the US.
If some universal ID system does appear in the US, it'll be government-backed, controversial, and take 20+ years to develop. The US is better off adding passwords to the SSN or biometrics or RFID ID/passport cards...
See also a very interesting presentation on Identity 2.0, as well as the sequel.