it would likely be built into the ID, like a PIV/CAC card. I thought about this same thing many years ago, the state DMV's could be in a PKI web of trust with a federal signer/issuer/cross-signer above them. Proving your identity online would mean inserting your ID into your computer so it could be crypto-graphically validated. Yes there are genuine privacy and other concerns, but we'll probably end up there anyway and could have avoided all the mess of having these crappy third party for profit companies involved. The tech already exists, and has existed for some time.