I am testing this right now -- someone pointed to the article after seeing my Blog post yesterday about very low priced OEM Windows 10 license keys.
Apparently, the Windows Installation tool still works, and an upgrade from a licensed Win 7 or Win 8.x system should complete and have a Digital License issued to it.
In a nutshell, got a Win 7 or 8.x system with a validated license?
Get the Windows Upgrade Tool here and go to business : https://www.microsoft.com/software-download/windows10
Test Report -- It WORKED 100% fine.
Windows 8.1 system now up to Windows 10 Pro version 1909, with Digital License and all.
Wonderful tip. Thanks @ryen !!
(re: your tip about ZDNews article about win7 and win8 free upgrade still possible)