Some of those stock houses already have so many older transparencies on file that a few more won't make much difference, unless its specifically contemporary subject matter. Things have sure changed. My brother would get four thousand dollars for one-time rights to publish a single 4x5 color transparency back in the mid-60's. Extrapolate that into today's currency! What digital has done is make anything equivalent worth about a five dollar remittance now, if you're lucky enough to get paid at all. So why would any 21st century photographer even bother? ... But Rol, neither you nor I belong to the 21C anyway.