[grandalf]

I realize that, but what aspects of it do you think are particularly hard in the example I used? Right now many people with 16GB phones have to go through a fairly painful manual process to avoid getting error messages/warnings about storage.

So while it is difficult, I think that from a product perspective there would be only upside to treating it as a cache compared with the horrible usability of a 16GB IOS device with a typical 2016 usage pattern.