Re: x86 emulation on ARM
Sandy Bridge hit the market almost six years ago, and I'd be pretty surprised if there was an ARM chip that could match a Sandy i5-2500 running x86 code, given the overhead of emulation.
Not only that, but why would buyers of the PC in question want to be limited to legacy software on their brand new computers (even budget PCs)?
In this day and age, the market has bifurcated into PCs and mobiles, and nearly everyone has an Android or iOS smart phone that (with the addition of a mouse, keyboard, and external display) is more than capable of doing the simple stuff that would be comparable to what a legacy PC could do, and for which there is already a huge library of apps.
Those of us who still stick with PCs often like them for reasons that would also rule out SoC-based ARM PCs running emulated x86... performance, upgradeability, that kind of thing. A fast ARM that wasn't engineered with the compromises necessary for battery-powered operation could be very quick running UWP apps... but there are few of them that are any good (and given the resistance to Windows 10, I doubt that's going to change any time soon), and running x86 incurs the emulation penalty.
I would also expect that MS will lock the bootloaders down so that it is not possible to install operating systems other than Windows 10 on these machines. If it were Asus or Acer or Lenovo or HP or any other mainly hardware vendor, it would be different, but MS has a vested interest in pushing Windows, and we already know that they're more interested in serving their own needs than those of the customer.
Rather than trying to expand into hardware, perhaps MS might want to release an OS that they don't have to force people to take.