[zAy0LfpBZLC8mAC]

> First, embed the "legacy" address space.

What do you mean by that?

> Second, have legacy-to-legacy connections use v4 on the wire.

Just as IPv6 does?

> Third, strongly encourage existing user-maintained configuration (config file formats etc.) to remain perfectly valid as long as they don't use v6 addresses (or other v6 features.)

Just as is the case with IPv6?

> You are right, you'd still need a "legacy" address to connect to "true" v4 servers, but that address would be all you need

Just as it is now?

> while most operating systems, routers, client and server software could be, technically, all-v6 all-the-time by now.

If they implemented the extensions ... just as if they implemented IPv6 by now?