Quite frankly, mounting an ISO really isn't that big a deal. Many want to mount their game discs as ISOs, (myself included), so they don't have to crank the CD or DVD in and out of an optical drive constantly. I tend to think M$ isn't going to include any capability to go around DRM to mount these discs, possibly running afoul of the DMCA.
So, business as usual, you'd still have to get a clean ISO someplace else, before Windows would mount it for you.