If anyone wants to help test something, someone who isn’t on 7.0.0 should try messaging me with this link:
I’m curious whether username links work with 6.47.1 clients.
Edit: It does 
So between this and that on older clients, people who are on 7.0.0 today should have phone number privacy from all Signal users even if the other end hasn’t upgraded to 7.0.0 yet.