Agreed. I want one if for no other reason then because this is literally the exact shit my friends and I used to pretend we had.
As for replacing phones all together. I don't think it'll be in watch form obviously, but potentially it will happen with contact lenses to some degree. I'm not sure about the audio though, that would have to be separate which complicates things. Could be in the form of contact lenses with accompanying earpiece/mic or some such.
If you're into Michio Kaku's ramblings then you'll have heard his belief that one day all this shit will literally just be implants in our brains like something straight outta sci-fi. It's really not very farfetched if you go far enough down the timeline.