Windows Mobile's Continuum functionality offers an interesting possibility for future smartphone buyers - the ability to have the smaller phone in their pocket that they demand whilst still being able to connect a larger screen for 'big picture' functionality.
Whilst only Microsoft does this right now there's no reason why Android or iOS users shouldn't gain the same functionality - in fact at least some of this capability is available on both the major mobile platforms.
The key to Continuum is that it allows the use of a larger screen and input device than the phone itself can handle. That's been exploited solely for the mobile to desktop category so far, but why stop there.
Imagine instead an iPhone SE sized device performing your day to day mobile needs, but also being able to attach to a larger iPad-like screen to become a tablet too. Add in a lap dock style accessory and the desktop dock functionality already demonstrated by HP and you really have one device that does everything.
Of course for Apple its probably a no go. Reducing the number of iPads it sells would be impossible to stomach. Android users can do a lot of this today. Except that I know of no current Android device that supports either second screen capability or the passback of keyboard and mouse inputs over Miracast. Both those items are Windows 10 Mobile exclusives.
Still, the concept itself is sound. Especially given the popularity of the iPhone SE (and to a lesser extent the Xperia Compact line). A powerful but but small smartphone will always have a ready market. A powerful but small smartphone with the ability to become a tablet, laptop or desktop becomes so much more.
Whilst its only Microsoft offering this capability don't expect to see it go mainstream any time soon.