A potential problem I see for Microsoft with this is convincing consumers that this is just an upgraded version of the Xbox One. The "PS4K" name is perfect, as it clearly indicates this is a version of the PS4, while also denoting an improvement of some kind.
With the One, I'm struggling to see how Microsoft could name this system without confusing consumers that this is an entirely separate system from the One.
The One Plus? One Elite? One Gold?
I think that will be the main challenge for Microsoft for their upgraded One, because as we know, branding and marketing is everything.
As a side note, how exciting is this? A beefier PS4 with a GPU that rivals a 970, an upgraded Xbox which will, presumably, have similar specs and performance, and Nintendo's NX. All coming well within the next year.