I am sure that workstation vendors who wish to support customers who run alternative OSes (even Win 7 or XP -- in use in the vast majority of large enterprises) will provide a hardware switch like the Chromebooks, or some other method of disablement.
Either that, or they will elect to exclude themselves from Microsoft's Win 8 branding program and this mandate for the bulk of their products.
It is doubtful they will want to prevent their corporate customers from running earlier versions of Windows.
|