I wonder which exact problem would that solve? Right now you can set an asset name in the metadata, isn’t it enough?
As for the proposed solution for the domain names, I don’t see why they can’t be attached to the account directly through your registration system. In the proposed solution you add an extra layer: registry → nft → account and suggest to determine registration based on the token if I understand it correctly. However, you also suggest to “expire” the name attached to the token. In the case of the expiration, what would token indicate/what would be the value of the token?
On the other hand, you can write a domain name registry contract and create a simple mapping(address => Registration) where Registraction is a struct with params like expiration date etc. This way you don’t need tokens to prove ownership, don’t have a problem giving meaning to the tokens that are expired and there is no need to extend the standard.
However, if you’d like to use token as collateral or transfer ownership rights through the NFT transfer I think you can set an expiration date on the token itself by checking block time upon transferring attempt and again, map token id to the domain name in another smart contract. This way you achieve the same goals without extending the contract.
I think this is similar (in a way) to my Metadata Manager ERC: you can build an abstraction that works on top of existing standard instead of extending the standard itself. The only difference in your use-case is adding logic for the expiration and duplication checks unless I misunderstood the idea.