In plain English: Anyone can install Windows 10 on a device or within a VM -- ignoring the prerequisite of Windows 7 or Windows 8.1 -- by using one of the beta's disk images (in .iso format) and run the preview indefinitely and free of charge as long as they remain on the Insider branch.
However, opt out of Insider -- as users can -- and that copy of Windows 10 will expire, and thus drop into some kind of degraded state. (At the very least Microsoft marks "non-genuine" copies with a watermark; there may be other ramifications, but the company's not yet spelled them out.)
"If you decide to opt-out of the program and upgrade to the 7/29 build, you will be subject to exactly the same terms and conditions that govern the offer that was extended to all Genuine Windows 7 and 8.1 customers," said Aul, referring to the limited-time free upgrade. "This is not a path to attain a license for Windows XP or Windows Vista systems. If your system upgraded from a Genuine Windows 7 or Windows 8.1 license, it will remain activated, but if not, you will be required to roll back to your previous OS version or acquire a new Windows 10 license. If you do not roll back or acquire a new license the build will eventually expire."
Again, in plain English: Abandon Insider and the "free" Windows 10 isn't free any longer, unless the test device was upgraded from an eligible Windows 7/8.1 PC, in which case the free upgrade offer applies.
Computerworld interpreted Aul's tweet of Sunday in that exact way, but because of Microsoft's confused messaging, that reading wasn't guaranteed to be correct. Now it is.
The loophole will continue to exist, assuming one can stomach the feature and change churn of Insider in perpetuity. But why? Microsoft can obviously detect machines equipped with Windows 10 and activated with one of the pre-release product keys. Also obvious is that Microsoft knows which systems were upgraded to the Windows 10 beta from an eligible Windows 7 or 8.1 OS. Why doesn't it just shut off the preview spigot to those who did not upgrade to Windows 10 within the limits of the free offer?
The simplest explanation is that Microsoft wanted to keep as many users as feasible on the Insider branch. Come July 29, it's likely that a large number of those now running the beta will opt out for the stable build, deserting the fast-changing, bleeding-edge previews.
Supporting that was Aul's original Friday post, where he labeled one section "Stay with us as a Windows Insider," and urged users to remain with the preview. "We hope that we'll continue to provide you great reasons to remain a Windows Insider," Aul said.
Sign up for MIS Asia eNewsletters.