Yeah, though we want sooner and I think they have to be sooner, other factors has to be completely ready and well executed before they release this elusive mystical "Surface Phone".
CShell for example, like Meteorhead says has to be ready, no less. Why? The Continuum on W10M is nothing but just underwhelming, it is literally like a tablet mode on an external display, but without good multitasking abilities like Windows Snap, let alone having a windowed apps. Everything that they have to do with this "Surface Phone" has to be polished, optimized, not buggy and fully-baked. CShell must be virtually indistinguishable from Windows 10 on PC, except for other things such as the lack of legacy components like Control Panel and other non-UWP-based ones.
Win32 emulation support is also needs to happen, which what Windows 10 ARM already bringing to the table. So that Windows 10 Mobile (or Windows 10 M) is able to run Win32 apps on same emulation technology on Continuum mode. This will make any Windows 10 M device become as good as regular desktop PC when docked onto something, bringing most if not all desktop apps used for productivity on Continuum.
In regards to that foldable device, I really have my skeptism about being ready as a product. The problem is that do we have a material that we can use for flexible displays that won't leave any wear marks in short amount of time? Also how sleek the device is. It sounds cool on paper at first, but the practicality will win the end. People are not really asking for it, unless Microsoft can actually deliver the great user experience and convince people with it.
Also, if the device rumored is not going to look like a phone as they want us to think. Then I think Surface Pocket would be better fit. Since these are devices that can fit on the pocket. Its like a return of Pocket PCs. I don't want to call them "ultramobile PC with telephony" which just sounds wordy and unnecessarily complicated.