I'm certainly interested to see how vendors (the BIOS/device ones) actually cope with the win8 requirements and leave documentation for the end user around that explains how they can install a different OS.
I just did this to a Sony system last week, and finding and disabling secure boot was trivial. There's really not much to it.
That makes the question: Should it be "one-button" to install a new OS? I somewhat doubt that is a valid argument in this case.