I wasn't referring to official policy, I'm in the real world discussing what will actually happen. Most motherboard vendors have trouble making a lot of 'mandatory' things that customers actually care about work. Just how much effort do you think they will put into making this stuff work beyond what is required to boot Windows 8 and get the little sticker?
How many motherboards have you fought to make power management work on? How about the temp/voltage/fan sensors? Last I heard working ACPI is also a requirement for the Windows logo program.
Now add in the fact that Microsoft is almost certain to be quietly 'encouraging' motherboard makers to break this particular feature. Raise your hand if you don't think an OEM would instantly get into the double secret marketing co-op program and qualify for special pricing or marketing kickbacks for discouraging OS migration?