We shall see what happens.... there has to be an ISO for devices MS targets non-WU updrates. Where, when and how are still questions.
MS has said once a machine is updrated, you can acquire an ISO - and do clean installs. I don't think the key is embedded in the ISO, it is derived from a qualifying previous OS.
I have got OEM RTM from mydigitallife. It appears to be official. Activated by itself.