We'll see how it plays out, but I imagine the notion of a file will continue to decline, and end up replaced by APIs.

APIs continue to provide interoperability, but instead of having the user select a file to upload, they select an image through the Facebook API. This should ultimately improve the user's experience, but there are some downsides during this transition period (IE: photoshop touch lack of sharing features).

While you could argue FilePicker brings back the file, you could also hedge your bets the other way, and work as much as possible to abstract away the file. Instead of grabbing Facebook photos as a set of files, what if I could easily grab the set of photos than contain me and a friend?