how win 10 works out its product ID that is tied to licence is a mystery but there is a very good chance that the changes being made to activation won't be enough to allow an entirely new pc to use an old licence from an oem upgrade. All the changes are there to do is let people who replace the motherboard do so without needing to contact Microsoft to reactivate it every time. I don't think it means open season and eternal Win 10 licence for every PC from now on, they want to stay in business I think.
If current install is a retail copy, you can move it freely now.