The old books are still available, as well as the aforementioned Pathfinder, and any one of these has enough adventures, class variations, and settings that anybody with a normal life as well as a gaming life would not be able to completely devour them in a lifetime. The makers of D&D have long had a problem with gamers finding it easy to ignore their releases of new editions. Imagine if the legal vagaries allowed an old partner of Microsoft to make a Windows 7 variant which then beat Windows 8 in sales, and you’re pretty close to the situation with D&D and Pathfinder at this point.
A new version of D&D is dawning that intends to unite the fractured fan base, as currently D&D is playing underdog to Pathfinder, a game which itself was based on D&D 3rd edition rules.
