Over the weekend a blog post by Microsoft's Gabe Aul (which has since been edited, presumably by the Microsoft legal team) created quite a lot of confusion about whether Windows 10 will be free for all users of the Windows 10 Technical Preview.
In short, it appears anyone running the Windows 10 Preview will be able to upgrade to Windows 10. The catch is that you need a genuine license of Windows 7 or Windows 8, but it appears Microsoft will not be performing any checks to verify if you really have such a license.
So technically, this loophole would allow someone to download an ISO of one of the latest preview builds of Windows 10, install the preview on a new or formatted system, and upgrade to the final version of Windows 10 next month without having to shelve out any money for a Windows license.
It's pretty much the same as pirating the operating system but based on our current understanding of the Windows 10 Tech Preview licensing mess it seems the software giant is going to allow this.
You could make the argument that Windows XP or Vista users can save themselves a couple hundred dollars and use this method to upgrade to Windows 10 for free but if a consumer is still using XP, the likelihood of them jumping to Windows 10 is small as they have remained entrenched with the decades old OS. And even if a few do, the bottom-line impact of this loophole is minimal, except in China, where piracy runs rampant. But in that case, do you believe those users, who already pirated Windows XP, were going to buy Windows 10 in the first place?