Haven't read the article yet, but my impression is that we're moving more towards a computer system in the philosophy of the one in Minority Report.
A modular, networked (among our nodes) system. If you have multiple devices, they'll all be intertwined. Processing power can be shared across them all (see: sony cell processors for an idea), as can information, environments, and input methods. Even Google Chrome (the browser) has some very, very basic version of this with browser syncing and Chrome-to-Phone. It's kluge-y and clunky, but it'll only get smoother. Flick a page/document/whatever from your ipad to your desktop when you walk into the house. Use your phone/pad as an input device/monitor for your main system. Spread video rendering across all your nodes (desktop, phone, laptop, ipad... toaster/refrigerator... whatever).
As OS X and iOS merge, this all becomes built-in. You may still have different interfaces for different nodes, but they'll be potentially interchangeable. Just like popping in and out of full screen. Or having states and versions saved. Or having more stuff on servers or talking between your systems at a distance (even if you have local copies, or local media that you don't keep off site).
In the end, I don't think this is a dumbing-down sort of simplification. I think it's a greater-level-of-sophistication sort of simplification. It looks simpler because it's more sophisticated.
