Internet censorship and login that ties to your real world ID. If it is implemented at the ISP and regulatory level.
In addition, mass surveillance grid with AI and facial recognition.
When we take out our phones, our locations are already tracked right now.
Because the blockchain record is permanent, we may think the technology is not there yet, but it is here. Just the matter of integration.
Even with BTC, all it takes is interacting with KYCed accounts, with each interaction the probability of identifying the real identify goes up.