I have to object to a statement like this. While it seems about everything that America invents winds-up in the legal system, the idea that D&D could have been an "empire" is just wrong-headed. D&D expanded regardless of TSR's smooth moves or missteps because it has always been a very player-driven game, the ultimate user-generated-content-game really. Just as much and for the same reasons, D&D never had that much potential to become that much larger than it did become. Only a certain type of person would play the game and not very much would stop them from playing. Some company might make more or less money from this culture but the size of the culture pretty strictly limits the profits involved.
It's worth noting that D&D 3.5 was released with an "open gaming license" and thus the game was forked by the Paizo company who maintain their Pathfinder system closer the original game than the present D&D 4.0 released by now-Hasbro-owned Wizards Of The Coast, which just reinforces that no single company is likely to create or destroy D&D-like role-playing.