Re: I wonder how well this would run Linux?
As for "Wacom and Linux drivers": To my best of knowledge the "official" drivers exist for the external grafik tablets NOT for the Penabled technology used in the S/P 1 and 2. The only Penabled drivers for "Linux" are the ones used by Samsung in the Note series and those are "Android", "Closed Source" and IIRC not available for purchase from third parties. There are "open source" drivers for the Penabled system but when I last looked they lacked basically all features that make a Wacom (or NTrig) pen. Basically the pen was recognized as a mouse (No pressure/tilt support, no button support etc)
The S/P3, S/P4 and S/3 all use NTrig and that is (partially) owned by a certain company in Redmond. That may or may not be a problem (MS actually DOES OpenSource and Linux stuff)
The WiFi module may be supported. The S/P2 and better can do MiraCast and that somewhat limits the choice of modules and makes an (open) documentation more liklely.
Grafik either is or soon will be supported for at least the "internal" chip. Intel does produce/support that after all. Any Skylake GPU new features may take a bit before they are available but I'd say they will.
Not sure about power saving modes. Linux is generally not up to the same capabilities as MS here when dealing with new Intel CPUs. I'd expect at least a delay until the systems can get to similar endurance levels / effective use. And depending on the drivers MS delivers with their own hardware they may not get there (MS knows the heat curves of the Surface better than outsiders and may run "optimized" throttlings)