I don't know about that.

There are a few paths forward, with different tradeoffs.

1. NIP-EE never gains much adoption and all major clients just use NIP-17. This is probably good enough for most, so long as everyone has a workable setup for DM relays, which means the clients will need to have reasonable defaults there. Users who change their DM inbox relays to ones that don't support auth will end up having recipient metadata leaked, but those who use appropriate relays will be fine. No one will have the content of their messages viewable by anyone else unless they somehow leak their private key, but they will have the benefit of being able to see all their conversations regardless of what client they log into.

2. NIP-EE gains traction and fully replaces NIP-17. This will result in extremely private DMs, including forward secrecy in case of a private key getting leaked. However, it will also result in not all DMs being visible if you use multiple clients. Only the messages you sent and received on that particular client will be visible, and you will have to remember which conversation is available on each client if you want to refer back to it or continue it. Those unaware of how forward privacy works will also see it as a bug and assume that Nostr DMs are simply broken since not all of their conversations are visible on all clients.

3. NIP-17 and NIP-EE are both used on Nostr, but in different contexts. NIP-17 is used in most clients for general messaging needs, and no clients remain that are using NIP-04, so you can be reasonably assured that folks you send a DM to will see your message. Meanwhile, there are separate clients for those who prefer the forward privacy of NIP-EE, and they know to alert the recipient that they are trying to connect with them privately by other means, since the recipient may not yet have a NIP-EE client. The downside here is that many people will still just use NIP-17 DMs for even their most sensitive communications, even though a better alternative is available, because that is the DM standard used in their favorite client.

4. The worst option... We just continue the same way things currently are, with some clients still using NIP-04, despite it being long deprecated; others using NIP-17 to greater or lesser effect based on how well they implemented it; and still others using NIP-EE. This mess will continue resulting in users having to figure out what type of message their intended recipient can receive and make sure they have a client that can send that type of message, or else what more commonly happens because most people don't know better: they will send a message with the assumption that their intended recipient will receive it without issue, only to later find out that they never saw the message because their client doesn't support that type of DM.

Of all of the above, I think I would prefer option 3, but 4 is the most likely to occur.