A computer without a filesystem that predated personal computers can be called a pre-PC device if you like ;-)

If a device has a filesystem for its own use but does not expose the filesystem to users or to applications, that's a post-PC device. If we merely denude the device of the Finder but all the apps use the filesystem, I'm on the fence. It's a post-PC device in all the ways that matter to users, but it feels transitional to me. Future generations of post-PC device won't expose a filesystem to developers or users.

So yes, iOS devices are post-PC devices, but they can become even more so.