Sir Whiskers said:
It's just a matter of reaching the point where buyers *have* to have something that they can't legally get elsewhere.
A few things will happen. In some cases, companies will be forced to back down, as M$ did with product activation for large-volume customers. In other cases, the competitive disadvantage of DRM will allow other companies to enter the market and succeed (open-source alternatives, for example). In the gaming market, this will provide an excellent opportunity for the small publisher. Given the nature of OGL, where your competitor is free to use large chunks of your work, you could really screw yourself if you are a big publisher. Put out 'Bunnies and Bandits' in an expensive .pdf where 75% of the work is freely copyable by your competitors and watch 'Rabbits and Robbers' appear next week in a $5 .pdf.
The fallacy is in assuming that DRM is intended to stop either large-scale piracy or the casual copying of the technologically savvy. It isn't, it won't, it can't, and the content companies know this.
What they are trying to stop is the small-scale casual copying between friends. This is where they lose (or at least think they are losing) a sale they would have otherwise gotten, and this is the only place DRM really works.
So, if eventually all gaming .pdfs are DRM'd, you'll have three (legal) choices:
1. Buy an expensive print copy you can share with friends, that is easy to read, and is relatively hard to lose, and requires no skill other than the ability to read. You can't easily copy content from it for inclusion in your own work, and you can't share it with more than one person at a time, encouraging the purchase of multiple copies.
2. Buy an expensive .pdf (because some publishers are afraid of cannabalizing print sales) with restrictive DRM that doesn't allow you to loan it to a friend, limits the utility that electronic publishing was supposed to provide (cut'n'paste, easy distribution, re-printing damaged or lost content, etc). This is ideal from the publishers point of view, as the cost of production is basically nil, and if they continue to not provide repeat downloads, even better because some people will be forced to buy it again.
3. Not buy the product at all.
3 is the worst-case for the publisher, because that generates zero revenue, and no repeat business. 2 is ideal for the publisher, because it maximizes profits and requires almost nothing in way of expenses, maintaining inventory, etc. 1 is not as good for the publisher as 2, but better than 3. They still make some money, but expenses are much higher.
From the consumer's standpoint, they will choose 2 last of all. There is no (or little) cost savings, reduced utility and increased hassle. If they really want the product, they will return to buying print products, or they will resort to dubious means to acquire an unencumbered .pdf. If it was a marginal purchase, they will likely just opt out of the purchase altogether.
The end result is that either prices on the .pdfs will have to be substantially lower than print (which risks alienating the retail channel) or that the .pdf market will die off. Selling PDFs that are DRM encumbered and as expensive as their paper counterparts is not a sustainable business model. You'll either destroy your business, or go back to being a print-only publisher for all intents and purposes.