As IT evolves it appears feasible that pretty soon the majority of people on the planet will soon have a very capable smart device with them. One thing that is lacking still is a consensus global identification app which could be utilised to identify a person across countries. This only requires coordination and enablement. Already a global ID system exists in the form of Passports. Another unique global system which exists is the phone numbers system which have country codes and numbers unique in the world.
Will it ever happen that a smartphone that a person carries will have an epassport and a phone number as an ID which can be used at airports. Here is my smartphone, it has my passport, my base country ID, my base country driving license, my phone number and here is me. In addition to that here is my linkedin, my facebook, my twitter and here is me.
The international credit card system is a very good example of coordination. It has a number, a name, an expiry and a CVC number. It is unique and can be used globally online.
There could be a similar global ID card and a global eID which works. If anyone opts in they will be a known Citizen of the World. If anyone opts out they will a disconnected individual who prefers some privacy.