In terms of column inches to delivered devices, Ubuntu Touch has all other smartphone platforms on the ropes. We seem to have been talking about the Ubuntu Unity8 desktop / mobile convergence for years, indeed it was announced way back in 2013. Two years before Microsoft launched Continuum.
Canonical has now announced the cessation of development of the mobile version of its platform.
I'd be inclined to say that a desktop convergence mode is the kiss of death and doesn't bode well for the Samsung Galaxy S8, but Ubuntu Touch had problems all of its own. The promise of external connectivity through Unity8 was the best that Ubuntu Touch had to offer, very little else materialised to give the platform a hope.
Convergance never actually made it to a shipping phone - of which there were few enough. The sum total of phones to have made it to market with Ubuntu is four - two from BQ and two from Meizu. There's a single tablet, also from BQ. Whilst some Android phones could have Ubuntu Touch sideloaded, there was little incentive for anybody but a few interested developers to do so.
When Windows 10 Mobile made it to market with Continuum, Ubuntu Touch lost its main selling point and any hope of a long-term future. Not that Windows has proved any more successful.
Desktop-like behaviour from your smartphone, when connected to the right external hardware, seems like a winning option, especially in developing markets where computers are still a rarity. Smartphone by day, desktop by night certainly sounds like an appealing combination. No-one has proven that it can be a strong selling point though.
If anybody can make it work, it will be Samsung. The Galaxy Note wasn't the first large-screen phone, nor the first with a pen. It was the first to do both properly though. My feeling is that the Samsung Galaxy S8 with DeX is the first to do smartphones as desktops properly. Presumably the Note 8 will support the same feature when it arrives and by this time next year we might be talking about mid-range Samsung phones that can also be desktops.
That's the sort of volume that could take the DeX into the mainstream and persuade other manufacturers, and eventually Google, to follow Samsung's lead - with catastrophic results for PC sales.