The Apple One
There is a very interesting selection of Apple concept designs here, but the one above stands out for me.
It looks ridiculous at first glance, but imagine something like this as a tool to carry around when you do not need a full-sized iPhone. It could be a decent camera, an adequate YouTube player and would be capable of communications in a variety of ways.
The problem is that the iPhone exists and so does the Apple Watch of which the latter is getting ore capable all of the time.