I see the current RPG market as similar to the cable renaissance.
Early on, the "Big Networks" were still king, but there were several cable channels that were starting to produce quality programming. Over time, the cable companies actually started eating into the market share of the networks in a significant fashion. The networks are still dominant players, but not so much that they can ignore cable channels and independent content producers.
Now, more than ever before, there are a horde of quality RPGs out there. No one game is likely to challenge D&D for market supremacy, but there are enough of them out there- including 4Ed's immediate and still quite popular predecessor- that the gamers out there have an embarrassment of riches.
The question, of course, is how many of those very good games can sell enough product to remain profitable. With good game design decisions overseen by people with an eye towards the bottom line, the answer could be "dozens."