...How? I mean, there's prior art all over: Steve Mann (https://en.wikipedia.org/wiki/Steve_Mann) has been doing this kind of thing since the '80s!
But yeah, lots of prior art on the ideas and even some implementations exist. Another source for what was/is obvious to those of ordinary skill this art would be the Wear-Hard Archives (http://www.haven.org/mailman/listinfo/wear-hard). I miss the days when that list was more active.
Never knew about that list; time for an archive trawl, I think. Thanks!
Though I suppose they may be thinking that common use-cases will involve rotating one's head down a bit while maintaining one's line of sight, similar to "looking over one's glasses", which would bring their screen between the user's eye and what one is looking at.