Any news about how upgrade will be done? I have Win10 and Win 8.1 on dual boot in here. I would be extremely happy if I could somehow merge Win10 and Win8.1 and have the new Win10 running on my PC, but I dont believe that will happen.
You definitely can't combine OS installs like that....no idea how that would even work hypothetically.
If you've done an upgrade to Windows 10 directly from 7 or 8.1 via Windows Update for the Insider program, you've seen something similar to what you'll see in the final version.