Been there before
"...create a version of Windows NT...optimized for multicore ARM or x86 processors..."
I remember when Windows NT was supported on the Alpha and other processors. A project I was involved in sold a system using NT/Alpha and then MS dropped support for non-x86, somewhat screwing over our customer.
So the lesson today boys & girls is that Windows is maybe adequate for use a beefy x86 box (oh yes, viruses excluded), but forget anything else.