“Microsoft will be this year the first company on the planet to have a consistent UI from the smart phone to the tablet to the slate, to the reader to the rich client and to the TV with our Metro UI,” he said. “We know the power of getting that consistent user experience is something our whole product portfolio will benefit from.”
This could indeed happen (assuming Win8 runs in ARM chips), but I don't think it's likely nor do I care all that much.
I'm kinda looking forward to seeing Windows 8 show up on tablets, but I don't care if it shows up on an ereader. First and foremost, most ereaders ship with the OS hidden from the user. That means it doesn't matter if it's running Windows CE (Ectaco Jetbook Color), Win8, Linux (Kindles, Kobo Touch), or Android (Nooks). Until someone hacks the device to get at the OS you usually cannot even tell which OS it is.
Also, if the device is a basic ereader (no Wifi or touchscreen) then I don't think it will even be worth hacking. There's not much you can with it, given the limited hardware. And if it does have decent specs then it will quickly be hacked into a tablet, just like the Nook Touch or Nook Color.
We're probably going to see Win8 on ATMs, signage, cash registers, and other places you don't expect (but can find Windows now). I'm not all that excited about those possibilities, either. If I cannot use the underlying OS then it doesn't matter to me what it is.