Earlier quoted context omitted.
I understand that those laws have been updated: that EU law is initially being adopted with appropriate changes, i.e. it won't reference the EU any more and will reference the UK instead (and isn't defined around citizenship anyway)
I have a similar understanding, what will be interesting is how the UK will enforce its rules. Facebook has its HQ in Ireland, which notable not in the UK. This also applies to most other US companies. Kinda makes me suspect that some companies will just ignore UK data protection law on the basis the UK can't do squat to enforce it.
That suggests they've spent 2 years explicitly lobbying for whatever UK law changes they want, and will probably quickly get them.