I wouldn't be so sure, I think the ultimate goal is to link your network activity to your government id, just like the way it's done in China. So the only root left is the government basically.
Are we talking about what actually happened, or are we talking about doomsday fantasies?
Well I think the goal is to link it with hackernews account such that ycombinator can accuratly measure how many of their startups you're interacting with.
The whole point of the California/Colorado laws is to provide an alternative to that. The whole point is that it provides a privacy preserving way to provide a signal about whether someone is in a particular age bracket, without requiring any kind of third party ID verification.
I am so puzzled by everyone who objects so strongly to these operating system based opt in systems; all it does is provide for a way for a parent to indicate the age of a child's account, and an API for apps and browsers to get that information. If you're the owner/admin of a system, you get to set that information however you want, and it's required that it only provides ranges and not specific birthdays in order to be privacy preserving.