It's a platonic ideal, but the internet runs on ads, and that ruins everything.
An interface you don't control is an interface you can't advertise on. The vast majority of players will never open their data in a manner that hurts their ability to sell sponsorship, and this problem is entrenched in the fabric of the internet.
HN is a very, very rare exception in that it never was and never will be dependent on ad funding.
I see everything moving to a ChromeOS-like model, with HTML+JS and WebGL for graphics-heavy things. If not those technologies in particular, something equivalent.
Essentially the consumer OS will be reduced to being a platform for a browser (I use "browser" loosely here -- I consider iOS to be an app browser in this sense). The OS will disappear from visibility.
To make this work you'll need a lot more standardization on APIs and data formats (because in the future consumers won't touch "files" anymore). I also think that's coming.
Finally, I see the server/client sides being even more divorced from each other. Clients will become dumber (single-purpose) and servers will become smarter (multi-purpose), and both will be much more connected.
An interface you don't control is an interface you can't advertise on. The vast majority of players will never open their data in a manner that hurts their ability to sell sponsorship, and this problem is entrenched in the fabric of the internet.
HN is a very, very rare exception in that it never was and never will be dependent on ad funding.