Concerning the original question, yes there is a lot of consolidation going on and I, for one, think it's a good thing.
Take a look at many of the products that were released within the first 6-12 months after 3E came out. How many would you seriously consider purchasing today, with their sloppy editing, inaccurate rules and mechanics, wildly unbalanced classes, etc.?
Now that most of us have gotten over the intial period of gorging, i.e., buying almost anything released, publishers are finding that to succeed they have to stand out among the pack. And because the economics of publishing won't allow many (if any) publishers to compete solely on price, we're seeing a marked increase in quality of content and presentation (which is intended to justify higher prices).
Of course, if we ever reach the point where only a small handful of companies produce all d20 material, we could have a problem. I just don't see that happening though - there will always be room for niche companies. There will always be ways for smaller start-ups to bypass the large companies (pdf's for instance). So we are not talking realistically about a monopoly over d20 material (I'll leave WOTC out of this discussion, since we're talking about the industry in general).
But the higher quality of the larger companies will force smaller companies to match the same standard. And, as a consumer, that's what I want.