So, my clean install of windows 10 preview will stop working and I have to recover my Windows 8.1 to get full Windows 10? Doesn't it sound really confusing?
The bottom line appears to be "MS is not giving away ANY free copies of WX on 7/29, just free upgrades for up to date licensed copies of W7 & W8.1 ." All the work done by the previewers, installing and maintaining preview copies, was GRATIS. Unless it was an upgrade.