Given that general design I imagine sleeping with the phone next to you in bed or in a cup holder shouldn't be much different than it is now - if anything the rotational flexibility provided by the magnetic puck charger would be advantageous in both situations.
Jony Ive has a thing for reducing devices to their core-most functionality. It's a design trait picked up from the likes of Deiter Rams. One of the easiest ways to reduce a device is to reduce or eliminate points of ingress. An iPhone which has no port for charging and the updated speakers from the Series 2 Apple Watch designed for waterproofing would be more ideal.
* Firm enough that you can pick up and move the watch about using only the puck as leverage.
Ive likes to associate himself with Rams, and people like to throw around the "as little design as possible" meme, but Ive and Rams are really very different in their execution of that idea, which counts for a lot. Ive is much more willing to challenge convention in his reductions, which sometimes pays off, but sometimes it means his products are a pain in the ass for the user to figure out when they ship. This can't be said of Rams.
Unless we invent seriously good wireless charging, I just can't see that happening. There's too many cases where having your phone "docked" just doesn't work.
Personally, I usually fall asleep with my phone laying on the bed next to me playing YouTube/Netflix/etc. No way to do that if it has to be resting on a pad like the Watch.
And what about cars and navigation? Can't throw your phone in your cup holder and pull up Maps anymore. You either need a new car with wireless charging or need to strap some sort of wireless charging pad to the back, which defeats the entire purpose of wireless charging.