SSN's were never to be used for identification, either. Once the mechanism is in place the government will always find a reason to stretch it beyond its original use - and statutory requirements seldom seem to matter.
If you don't see the constitutional dangers in this, ask yourself whether you'd want yet another massive government bureaucracy. Administering a NID card would require one - with all its inefficient, lazy, unfirable workers. Think IRS 2.
national id card gains support
From today's Washington Post.
I've been long w/VISG, a facial ID company.
If you can't whip 'em, join 'em...