Here's why this matters: Microsoft officials continue to claim that Continuum -- the capability that will allow Windows 10 Mobile devices to connect to external displays and keyboards -- is going to be a key for the company, its partners and its customers. There's been one very big limitation to Continuum so far, however: It only allows users to run Universal Windows Platform (UWP), and not full-fledged x86 apps.
What if an ARM64-based device could run x86 apps via emulation, the same way that the WOW (Windows on Windows) emulator allowed 32-bit apps to run on 64-bit Windows? That would make Windows 10 Mobile, which as of now, continues to support ARM only, and Continuum a lot more interesting, especially to business users who need certain Win32/line-of-business apps.
My sources say the "C" in this stands for "Cobalt," which is the codename for x86 emulation on ARM. (Cobalt also is Mojang-related, as is Redstone.)
My guess is the HP here is HP, as HP has been working increasingly closely with Microsoft on its Windows 10 PCs and the HP Elite x3 Windows Phone. (Maybe the "E" is for emulation?)
HP officials told me a month or so ago that the majority of enterprise users of its Elite x3 who wanted to run x86 apps via Continuum already had some kind of remote-desktop capabilities, primarily via Citrix, that enabled them to access their x86/line-of-business apps. HP reworked its HP Workspace viruatization service so that it targeted smaller business customers who didn't have x86 app access but lacked corporate remote-desktop access to be able to tap into their x86 apps.
A solid emulation capability included in the operating system would lessen, if not obviate completely, the need for these kinds of virtualization services, at least in theory.
I'm hearing this Cobalt technology is aimed at phone and possibly tablet/desktop devices, not servers. I'd expect the initial target audience for devices with the x86 emulator on ARM64 would be aimed at business users, as they're the ones who most need x86/line-of-business apps.