If this is true, then Windows 8 is not a true successor to Windows 7. Current desktop/server apps assume binary compatibility with x86. This sounds much more like a scaled-up version of Windows Phone.
It's just like the Mac Intel transition, but without an emulator to fill in the gaps.
Building an x86 emulator is easy. Building one that can run Windows 8 software at speeds comparable to then current Intel or AMD x86 processors will probably be impossible. There is no such performance gap between ARM and x86.
I can see ARM being great for corporate desktops: .net LOB apps work, IE will work, Office will work etc.
The performance of a built-for-speed x86 is very forgiving. Eclipse runs well enough on my Core i5, but I suspect it would have problems on an energy-efficient ARM.