I don't see any reason to make sweeping predictions.
I haven't actually seen RoD yet, but all the previews and talk I have heard so far make it sound like a true dog. So for now I'm going to just assume that it really is an awful book.
Draconomicon was awesome. After it came out, there were some people that complained that later books did not live up to the standard that Draconomicon set. IMO, we should simply be happy that we got such an outstanding book and expect future products to tend to be closer to average.
Well, if RoD is a complete dog, then the same thinking still applies. You can be disappointed about the missed chance. But you should still expect future products to be closer to average.
Now if the next few products were to establish a pattern of dogs, then that would be another matter altogether. But there is no reason to expect that yet.
One pattern I do note is the new races. Races of Stone was a decent book, but a third of it was spent on Goliaths. I don't have any problem with throwing some new races out and seeing what people like. But to just jump in with a new race and give it just as much supporting material as dwarves receive is, IMO, a really stupid move. It appears we are getting the same treatment with Illumians. sigh.....
I'll assume that Races of the Wild we also be the same. So that is a big push for me to not buy that. Basically they will need to convince me that 2/3 of a book is worth buying the whole thing. That will be hard to do.
But I expect to still buy other upcoming stuff. One outlier, up or down, does not establish a trend.