Windows 10 absolutely must have a 'Windows RT' mode to lock it down from malware and other crud. Otherwise MS will just be handing the grandma and education market right over to Chrome. Or let Windows on ARM live..
I would like to see an ARM version of Windows 10 with no desktop for education and consumption. This would eventually be the future as Metro inevitably overtakes Win 32.
Right now, a Cherry trail 10.6 inch Surface with a 'Windows RT' mode would be perfect for my needs.
There will be a version of Windows10 for portable devices that runs on ARM. The preview launches later in the year. They're doing desktop first to get all the corporate and enterprise stuff correct.