It seems to go in pulses. You get a new breakthrough idea that sets the standard and "teaches" people what they wanted but did not know of themselves before the product was in their hands. Then competition works to perfect whatever breakthrough that was. Milking the cow while it is what people want. Then it all happens again.
I can't say I was impressed by any of the improvements done by the previous mobile phone generation before the touch-phones. So there too you had the same thing. Nokia etc gave us something new that we wanted, it was fine-tuned, improved and had some arbitrary features added to them, and then came the smartphone/touchphones.
So what will be next up? Well if I knew I wouldn't be here.
(Or actually, I would, as I quite like my job).
But I think it's obvious that we don't need advanced computing power inside every unit we use (phone + tablet + PC + laptop + smart-TV + smart-watch + smart-toaster..) instead we will own our access to a server that stores what we own and provides the data that the device we currently hold needs to display , not necessarily run. So I think we'll have anything that can become a screen or a surface to write on, made most convenient for the use-case, which we will then connect to the web and then run whatever applications we need.
You are absolutely spot on about these things coming in pulses. That way people get new features and the companies get their profits! Win-Win.
As for what's next, yes, everything is going to get 'smart' and connected and you are right that we wouldn't need powerful chips in every single thing. That would be waste of resources. And yeah, AR will play a huge role as I think the whole of computing industry could go towards that direction. It would also enable any surface to be used as screen. If only companies can figure out to integrate this tech in some kind of simple glasses that are indistinguishable from the regular sunglasses and maybe even in contact lenses!