Fernando, I agree with you, except for the loosing spanish nationality for european one. But come to think of it, I guess it would end up being something more the way the United States is set up- each state has an individual ID, but we all share the same passport.

However, in the US, we have the advantage of sharing a common language (for the most part!). However, I don't think the EU is so far away from what you say, so what if the europeans don't share a passport, I already think that there is much more cooperation between the countries than there was before, after all, that's half the reason the EU works! As in the US, each state, has their own constitution and laws, but in the end have to abide by the federal constitution and laws, states don't loose their identity but manage to live in harmony with the rest. How is the EU much more different from this?