Windows 10 S as a mode sounds all too nutty. Basically, 10 S is nothing short of a version of Windows 10 that only allowed select Apps from the Windows Store to be installed on it. It pretty much runs the same as a full version of 10, but just had some limitations on how you could use it. As it stood, this was also a great chance to get Windows 10 on an ARM (mobile) device as well. We saw the "always on" PC's debut this year, and between those devices and a 'cut' version of Win 10, things looked good. In fact, they looked so good, there were even rumors of the "Surface Phone" emerging once again.
Well, not to be the bearer of bad news here, but there is no Surface Phone to be seen at this time, nor do I think Microsoft will ever be dumb enough to call a device the "Surface Phone". However, that doesn't mean that they will not have something that would compete in the mobile device space. Imagine if you will, an ultra small 'Surface Tablet" that is about 6" in size with a 18:9 screen and a cellular radio on board. It has 8GB of RAM, 256GB of internal storage and 4,000mAh battery on board so it will last all day long. It also and be used with something similar to that Continuum Dock, with a few small tweaks...
The new dock features additional bays for storage solutions, more RAM, a stronger graphics chipset and the ability to 'switch' the device into full Windows 10 Pro mode. So when you undock, you get only the Microsoft Store content, but when you plug in to your dock, all your EXE files are in place and ready to run. When you are away, you can plan you standard games from the Windows Store, but when you get home, the stronger graphics of the docking station can play anything you can toss at it. It may be a pipedream, but it's a pretty brilliant one. If Microsoft could pull something like this off, especially if they could tie in Windows 10 X-Box content to the dock as well, you could see a complete dominance in the hardware market from them in the future.
Selling the device in the $750-1000 range and the dock being an additional $200-1200 depending on storage selection and graphics card, will give just about everyone access to the device and would make it very tempting for carriers to offer as an option against the newer iPhone and Android offerings. Remember, most of the leg work has already been done in making all of this tech work seamlessly together, now it's just time to make it happen.