It needs to be free
If you must have a working Windows 10 machine in your home or office but won't work on it all day and don't want a new PC, I think an upgraded Netbook will do a better the job.
I imagine most of the earlier Netbooks are running Linux or Windows XP, so aren't upgradeable for free as it stands.Paying for a license wouldn't be sensible in these cases.
So, a prediction : Microsoft will eventually decide to sweep all those existing netbooks into the fold, by offering a free full installation.
I might take them up on that (on a separate drive), if only in the principle of "Know Your Enemy".