Earlier this week I was asked what type of new old school adventure modules would interest me enough to part with what little money I have that doesn't go to basic survival or paying off the huge cancer bills. I looked at the boxes of modules from TSR, Judges Guild, Mayfair Games, etc. I have from the 1970s and 1980s -- that's probably 300 or 400 modules -- (plus modules from old Dragon, old White Dwarf, and old Dungeon magazines) and realized that I would be unlikely to pay the high per page (and shipping) costs associated with old school modules today unless the module was something I knew in advance that I would love as much as Tegel Manor, Keep on the Borderlands, the City-State of the Invincible Overlord, etc. And there aren't many modules likely to do that.
About all I buy these days are PDF copies of magazines like Knockspell and Fight On! (as I can be pretty sure that there will be something in each issue that will be worth the money even if Sturgeon's Law applies to the issue as a whole -- which it hasn't yet) and PDF copies of rules that look interesting. I'd rather have hardcopies, but shipping them is too expensive for me.
Let's face it. I'm a horrible target for publishers. I prefer to homebrew my settings and adventures, I already have more published adventures I can could ever use even if I never created another homebrew adventure, and I have very little money to spend on new material just to support it. While most old school gamers aren't unlucky enough to be in my financial condition, I suspect the majority of us homebrew and already own more published adventures than we could ever use.
This means that as long as we are around, the hobby of playing old school style games isn't going to die even if no new old school material is ever created by the RPG industry. However, if a part of RPG industry is going to survive on publishing old school material, this means they probably need to really concentrate on getting more old school players into the the hobby.
To be honest, I get the impression that a lot of the success of old school publishers thus far has depended on a (relatively) small group of long time old school players buying material they don't really need because they want to support the publication of old school material. I know if I wasn't spending all my disposable income on cancer bills, I'd be doing just that. While this may be great for jump-starting things, it can only go on for a limited time before people burn out on doing this -- especially as more and more companies create old school material and try to sell it. If an old-school RPG industry is going to survive, let alone thrive, they are going to have to find a way to attract a good number of new players to old school play. New players will not already possess 10 or 20 modules (let alone a few hundred as I do), copies of every major rule system out there, etc. and would therefore be a much better market for new old school products than old grognards like me.
Note that I said the RPG industry needs to to that, not the old school hobby. The old school hobby can easily thrive with a slow trickle of new players, it's the industry who need a steady and larger stream of new players, therefore most of the work of getting those players is going to have to fall on the industry. I've recruited seven new old school players over the last year. That fills up my game, so I doubt I will recruit nearly that many this year. I don't need more, but the industry does if it is to have a real chance of thriving.