Historically, Microsoft has never officially supported upgrading from pre-release versions of Windows to a final shipping version. And we’ve seen it in Windows 7 and Windows 8 to 8.1. Will this be changed this time around in Windows 10?
On December 4, someone asked Microsoft’s Gabe Aul, who has emerged as the face of the Windows Technical Preview, at least on Twitter, whether we as the testers would be able to update to the RTM version when it ships? And Mr. Aul responded in the affirmative: “Yes, that is our intent.“
— Gabriel Aul (@GabeAul) December 4, 2014
The answer is very encouraging. And the result will be a lot more welcome to push people to test the beta of the next version of Windows more seriously and thoroughly.
So the answer for now whether the TP version of Windows 10 can be upgraded to the final RTM version is a tentative yes. But considering the way how the new builds get upgraded in the installed version of Windows 10 TP, it very most likely will.