I would hope that the drivers that work in Win7-Win8.1 will also work in Win10. So far I have not run into any issues with my PC and the drivers in Win10TP.
Remember back when you could put MS Office on a desktop and a laptop? Windows 2013 came out and can only be put on one PC or one laptop.
Could it be that Windows 10 will be tied forever to the first computer it's installed on? That would make sense for the bottom line. And it would end the era of building a new computer and putting Windows 10 on it from the one that had cratered. OEMs are already that way, so it's something to think about.
Windows 8/8.1 was OEM only with no retail transferable licenses so this is nothing new.
Retail versions are usually way to expensive but come with the ability to use the same media and activation key to install on several computers,
OEM's are cheaper because it's one computer install tied to the motherboard,
Upgrade media is even more complicated to install cleanly without the original upgraded os installed first may hours but the amazing Brink has a reg file to stream line that little snag
My MSDN Windows 8/8.1 product keys are listed as Retail keys?
That is probably for ease of use, Windows 8/8.1 was never sold as retail only oem.
WMC upgrade EULA:
You may transfer Get Genuine Windows software, Pro Pack or Media
Center Pack software only together with the licensed computer.
I see Retail versions listed on NewEgg, well they say Packaging: Retail. I guess that's debatable what that actually means though?