They way they talk about the UI makes it sound like they are now working on just one UI that morphs to the target platform. One might call it responsive, though not truly since it would probably only have 3 main modes and variations on those based on your screen size. Certainly beneficial to not have to completely separate UI styles and code paths with different features here and there.
I mean it looks like it too, definitely elements of the new library in there.
I'm guessing that the way it will work on the desktop end is that you'll get a checkbox for "if a controllers is detected, use controller UI", similar to how you can currently do with BPM overlay. With the addition maybe being that the whole library interface could change to controller UI, not just the overlay as it is now.
Looking at the video though, there are still some stuff there that doesn't look like it's fully controller enabled so to speak. Like early on when he's scrolling through the sections of the Hades library page, it just shows those right side elements from the current desktop library as is, which are definitely mouse driven. Very doable on touchpad or touch screen but maybe not ideal for controller.
Countdown to old BPM getting deprecated starts now.
Thought now that I think about it, have they said about anything about SteamOS 3 on desktop? As far as I recall older SteamOS' would boot straight into BPM on desktop, or at least that was an option. I wonder what the plan is there.
Too many question!