Arent OEM licenses purchased independently of a device (I.e. not pre-installed) transferable anyway now?
Edit: jeese I wish I hadn't Googled that! It's a complete mess out there. But this is what I think the previous situations were:
Windows 7 Retail can be transferred.
Windows 7 OEM cannot be transferred, and cannot be purchased by end users.
Windows 8 Retail can be transferred.
Windows 8 OEM can be transferred, and can be purchased by end users.
Windows 8.1 Retail can be transferred.
Windows 8.1 OEM cannot be transferred, and also cannot be purchased by end users.
So good only knows what the terms of Windows 10 will be!
(Note, the 'cannot be purchased by end users' bit is more of a technicality than an actual blocker. The terms of 7/8.1 OEM System Builder licenses mean they should only be purchased by people who build and then sell the PCs to end users with the OS pre-installed. Nobody building their own PC
should be buying OEM licenses, but I don't see any way they can actually check that?)
Edit 2: OK I did more digging. As a base line, there are 2 types of licenses, Retail (also known as Fully Package Product, or FPP), and OEM (also known as System Builder). Usually this means this: Retail is your off the shelf product. Fully transferable, purchasable by end users. OEM is for System Builders, people who make and then sell machines with Windows pre-installed. OEM cannot be purchased by an end user as the terms are that it's only to be bought by manufacturers.
But, Microsoft broke this in the terms for Windows 8 OEM (note, 8 only, not 8.1). For 8 they added the Personal Use Licence to the terms of the OEM/System Builder agreement. This allows end users to buy OEM and install on machines they have built themselves. It's also transferable.
http://www.microsoft.com/oem/en/licensing/sblicensing/Pages/windows-licensing-for-personal-use.aspx#fbid=mfHEmav5xQp
This was only for Windows 8 however. In 8.1 they have removed the Personal Use Licence. It's now back to Retail for end users and OEM for System Builders, with OEM back to being non transferable.
What I've not found yet is what happens when you upgrade. I.e. if you bought 8 OEM and upgraded to 8.1, do you still have a Personal Use Licence?
I suspect this is why there was all those issues with clean installing 8.1 using 8 keys, and why 8 isnt supported as an upgrade path to 10. It suggests that 10 licencing will follow the structure of 7/8.1, and not have a Personal Use Licence like 8.
Edit 3: Actually, if 10 does follow the license structure of 7/8.1, would they even be able to turn Retail into OEM as people fear? The terms of OEM 7/8.1 do not permit users to buy the OS and install it on a machine for themselves, which is almost certainly what every single Retail 7/8.1 install has been used as. So turning all Retail 7/8.1 licenses into OEM System Builder 10 licenses under these terms would then immediately make them all non-genuine according to Microsofts own licensing agreements!
So in summary, if they turn 7/8.1 Retail licenses into OEM 10 licenses that follow the 8 terms, they will be transferable, and if they turn them into OEM 10 licenses that follow the 7/8.1 terms, they will be illegal! So the options are Retail to Retail, Retail to transferable OEM, or Retail to something entirely new and unique to 10. Place your bets now!