I do not understand the reasoning for wanting to deprecate NIP-08.
The advantage of NIP-08 is that the format of references is strictly in the domain of the client. A client can interpret and render a reference any way it desires, because the reference is always transmitted as #[n] with a "p" tag.
The existence of the "p" tag allows clients to query relays for notes that refer to certain authors. That's a valuable feature. I want to be able to query relays to see who is publicly referring to me, or to you.
The disadvantage of NIP-08 is that people can query relays to see who is mentioned in a DM. That's bad. DMs need to be private. My solution to that would be to add a "dm-tags" field with encrypted "p" tags to the kind-4 (DM) event. The client could decrypt it and render the references as usual. That's not a hard thing to do.
The advantage to NIP-27 is that it creates a new url prefix `nostr:` for all manner of uses.
Using NIP-27 for mentions prevents the creation of "p" tags. That's good for DMs, but it also allows authors to publicly gossip about other authors without alerting the subjects of that gossip. i.e. NIP-27 references support sub-tweeting (sub-noting).
My strategy in more-speech so far is to make NIP-08 references convenient by allowing the user to type @
>From: Giszmo at 04/23/23 16:41:49 on wss://relay.nostriches.org
>---------------
>So a profile referenced in a p-tag would be exclusively for notifications and in the content for display. Slightly more bytes than keeping nip-08 alive but simpler and complete for sure.
>
>Should we mark nip-08 as obsoleted by nip-27 or are there any strong objections? Clients will probably forever want to render these first text notes correctly but maybe if clients stopped authoring them, it could be a lower priority task in every new client.