If this works well
Intel should be afraid.
A re-written windows without bloat but with all the office compatibility on ARM could be very interesting. Office clients tend to be under the 4gb level so 64bit isn't a huge deal and bigger ARM chips are on their way.
While office on pure tablet probably isn't a massive draw, getting a transformer-type device which happens to be able to double as a light laptop with full MSOffice could be compelling enough to get significant market share via corporate purchasing. Windows on tablet also takes away momentum towards android and linux on the tablet (and desktop).
It might also have big implications for the VDI crowd. I wonder what the relative costs of headless ARM vs VMware are? It will be interesting to see if this will play out as a defensive move by MS to stave off interest in other OS's or if they will try for Apple's fat profit margin.
Of course, this assume MS can execute well. It is possible that the complexity of Windows and Office is just too great to work well on ARM and may lead to a disappointing experience.