Yup, this is Windows Continuum.
https://support.microsoft.com/en-us/help/17280/windows-10-mobile-continuum
It's neat, though I'm still bitter that Microsoft dropped Windows RT and their respective Surface RT devices when they could have just implemented this mobile OS there. Not going to buy more betas Microsoft.

And I already mentioned it in another thread this Friday. Google is also going this way with Andromeda.
http://www.techradar.com/news/software/operating-systems/google-andromeda-everything-you-need-to-know-1329834

Despite the fact that I don't think highly of continuum, I fully expect iOS and Android to implement it in their mobile operating systems eventually, and out of the 3, iOS is in the best position to pull such feature off. They've got developers support, they've got a user-base that moves on to the latest software by pressing a single button, they've got the best mobile CPU in the market that's capable of putting an impressive sustained performance with minimal to no throttling, and they obviously want iOS to morph into something bigger than just an OS for smartphones, iOS developers want that too.

Also, Ubuntu implementation is superior to that of Windows:

View on YouTube

That 6''-phone is almost as big as my Windows-tablet... and that tablet has a full Windows 10 version, not a dumbed down Windows Phone version. It was also a lot cheaper (even together with the costs for my Android phone) and has a full MS Office version as a bonus.

If you don't absolutely need to have all functions in one device, two separate devices are often better than one hybrid which is jack of all trades, master of none.

Yeah i can see the NX being very similar to this.

TBH i could see this being mainstream 10 years from now when the technology is more polished and powerful.   

This is what Ubuntu phone was supposed to be, but once again M$ beats them to the punch.