> "I am not sure how much the total users of smart phones have their own cloud. I would guess, not too much."
You're absolutely correct there. The question you asked was "Would you switch Anon?" So I was answering from my own perspective. I would not, but that doesn't mean it wouldn't be useful for those who won't or can't run their own home server.
> "Also having such thing, would allow you to have such servers locally, and use it transfer files e.g. between your devices without internet."
If you're going to run such a server locally, it's probably best to just run a home server. That said, I could see it being easier to just run a program on your PC that turns a directory on it into a local cloud that can be accessed by other devices on the local network.
> "The cool thing about having a layer like this, with the nostr level abstraction, is that it is easy to switch, and gives superpowers to apps with interop."
The power of protocols, for sure! Build an app that "speaks the same language" as the server that has the data, and your users can easily connect your app with their data, secured with their private key.
Not sure I would want to tie something like this to my Nostr keys, though. Or at least not to the same key I use for social media clients. We've seen already that keys can easily end up compromised, and if using this with encrypted file storage, a compromised private key would mean anyone who got access to it would also have access to your encrypted files.
Yes, that would make it less convenient, but it also depends on what types of files you are storing and how destructive to your life it would be if they were accessible by a malicious actor.