There are HUGE leaps that have to happen before the doomsday scenario you are putting forth could happen, I just don't see that happening.
Nobody ever does see it happening until it is too late. If they came out and said, we want DNA whether you commit a crime or not and we are going to use it for everything from criminal investigations to scholarships people would riot in the streets. It can't happen that way. If they take it now for arrests only , then in a few years, health care is having issues so they want to better identify health problems, so that gets tacked on , then a few years later if you want to be a patriotic citizen then you surely wouldn't object to linking financial and personal information to your id, I mean you have nothing to hide right ? The people doing this are probably not even thinking along those lines, but it will slowly lead to that.
It has happened with almost every thing we are guaranteed under the law. People object to something if you blatantly force it on them, but do it slow enough and it is like the frog+water experiment.
Anytime the gov proposes anything I try to look at the long term implication, not just what it will do right now.
They have a backlog of 500,000 + dna samples that need processing, over half are expected to be for crimes that are beyond the statute of limitations, yet they will be added to codis.