Part of the problem with using these older cameras for stock photos is that the stock agencies ( like Getty ) are demanding larger and larger files. I think Getty's spec is now something like 50meg, which, these older, smaller sensors just can't do. You pretty much have to be up in a sensor range of 15 to 18 megapixel minimum to get the filesize. I suspect that part of why they are doing that is to effectively force us to stay up fairly close to the leading edge of technology. Stock photos is truly a game where they ( the agency ) is in the drivers seat. They are laughing all the way to the bank, while the independent photographers are struggling to make it happen in the field, just hoping that enough images get sold to make this pay off in the long run.
In other words, if you think you are going to get rich shooting stock.....good luck on that. Lot's of competition, so you'd better be not only on the cutting edge, but also seriously on your game at all times.