You forgot important thing: There will always be some security guy yelling that leaking your internal IP structure is bad.

There will also be another clown that does IP whitelisting as security measure and refuses to just whitelist single /64|/24 network "because it is too wide" (I literally had this conversation last week with one of the clients)

> - The entire internet would be hosting home servers if not for the evils of NAT.

ISPs will find a way to fuck up