Sony, for example showed three products that disaggregate the handset to make it more useful. They showed off a tiny earpiece that enables voice and gesture control of the smartphone that it's Bluetooth tethered to. Although still slightly nerdy-looking, it potentially removes the need to constantly pull out a phone or tap a watch.
Even more radical was the companion camera device. This moves the camera phone to a lanyard or shirt clip. Again, a modicum of AI enables the camera to decide when to take a photo (life-blog style) or it can simply be removed and used to snap selfies to our heart's content. It's similar in concept to the Microsoft Sensecam concept that never saw the light of day.
Sony also showed a projector that turns any surface into a touch screen. This piece of the disaggregation puzzle allows entertainment and more complex use cases (booking a holiday, shopping) that are beyond voice control at the moment to be executed without removing the phone from our pockets.
Away from Sony, I met with Coin, a San Francisco startup who have created an HDK and SDK that enable secure NFC payment to be built into any device for a few dollars. Coin therefore vastly extends the number of devices that can provide touch payment so that rather than being restricted to a watch or a phone, many more pieces of kit (e.g. a wearable camera) can act as a payment card.
At the moment all of this technology (except Coin) is concept-only, but I think that it hints at a near future where AI, improved power management and available HDKs for common functions will lead to further evolution of the phone format. Perhaps by MWC 2020 the phone will no longer be the killer mobile tech and we'll all be talking about AI earpieces and personal area networking. We'll see.