Player designed scenarios are of course something that should flow next. Perhaps by individual gamers doing the 'odd one or two scenarios here and there, it would add up to a 10 or 20 scenario set in itself. I'd love to design a scenario or two but not a whole book or box like Jay and Mike manage to do.
If it became a popular 'hobby' I have no doubt that Shad could add a new section within PGHQ of player designed scenarios.