Re: And who told you I want to be measured?
That's precisely how pretty much every ISP that has implemented v6 has done it:
1, although every device behind has a routable address, inbound connections are blocked by default, you can enable them if you want.
2, no isp is v6 only, they are all dual stack for now, if your client devices support v6 they will use it by default otherwise they will fall back to v4, it will usually be transparent and sites that use v6 will be accessed in that way without you even realising.
3, in some cases your v4 is natted by the isp and not just by your own router, so you cant control port forwards etc... the only way to allow any inbound connectivity is via v6, which you control.
4, most systems support ipv6 privacy addressing whereby the clients will generate random addresses within your own local (/64 huge) range for making outbound connections, as far as the remote end is concerned a /64 is equivalent to a single ipv4 address - one network that might contain any number of devices, and advertisers etc will use other means (cookies, browser fingerprinting etc) to try and identify unique users or devices just like they do now.
with v6 you're no worse off, you're better off