Why not move the Masternode network completely and solely into the IPv6 space.
Every node could have an arbitrary amount of addresses, bound to an arbitrary amount of wallets.
The node addresses could even be changed all the time by some maintenance protocol.
How would non-IPv6 clients be able to connect to a masternode? I believe most end users like myself currently do not have access to IPv6 through their ISP.
Could MNs run their own DNS service - no more need for a fixed IP?
Not sure exactly what problem this would solve. AFAIK there is also no requirement for a fixed IP currently. The protocol allows to send a dsee message to update the address of a masternode for a VIN.
Really? So I can change the IP of my server (or have my ISP periodically assign me a new one if I'm running a MN on my domestic connection,) keep everything else the same, and it will still work? Guess I missed that memo.
Do you not still have to update your local/remote .conf files with the new server IP?
No, I'm just saying that the protocol allows it. You would still need to change your conf and restart the client to generate the dsee message again. Although nothing prevents anyone to change the client to detect a change of IP address and send an updated dsee to the network. You might even be able to implement this in a script without touching the client: when IP changes, kill darkcoind and restart it with the new IP address.
Edit: Thinking about this futher, this is probably not practical with a locked wallet, as it would need to be unlocked each time to generate the updated dsee message.