I wouldn't mistake the short-term lull in smartphone innovation as a long-term lull in mobile device innovation. Once they've got AR displays down to a reasonable size the power requirements will keep fuel on the fire for another two decades.
I'm not so sure. I reckon Apple are doubling-down on AR and are going hell for leather improving the performance of their mobile chips in order to offer a noticeably better experience when the time comes. Just a theory.