> Won't you always be able to use it for local networks?

Well for me until Linux shall support IPv4 my machines shall be on IPv4 behind NAT. And yet I'm enjoying IPv6 with my ISP-provider router transparently doing the heavy lifting and using IPv6.

> and completely block outgoing and incoming per-device-IPv6.

Same. I do just that: it's disable by a kernel parameter, in sysctl and in the firewall, just in case I'd mess up and re-enable one or two of these.

You can pry IPv4 on my LAN from my cold dead hands.