I think it is 75 years from creation of the work. That is an awful lot of time, as patents last way shorter. One should never say that because its old its no longer of any valuee. Ninty are releasing their old treasure troves of NES and SNES games on the Wii now for a pittance.
It is only fair that they who paid for it back in the days also get to decide when to start selling it again.
As for SH1, I doubt it will be re-released again, but who knows. In some years Ubi soft might decide to offer their entire back catalog as cheap downloads