I have some record albums from the 1950's. A few years ago, I checked around and they weren't available anywhere, even used, not no-how not no-way.
But recently I noticed them showing up on Amazon as mp3 downloads. Evidently, record companies are finally going through their back catalogs and making this stuff available again.
It's happening more and more with old paperback books, too, showing up as kindle books or collections on a dvd.
It hasn't happened yet for, say, made-for-TV movies produced in the 1970s.
I also think there'd be money to be made in simply producing an online archive of Channel 7 News broadcasts from 1975. Wouldn't that be fun to look at now and then?