The store that I visit sometimes to buy games here in Germany has more Pathfinder stuff than 4E. That is because most of the 4E stuff has not been translated into german, but there is a lot of german Pathfinder stuff.
Now, does that say anything about the state of the revenue of 4E products? I say, no.
Here is what I think happened: when WotC introduced 4E everything was supposed to be a core product. That is why we saw PHB 1, then PHB 2, then PHB 3. And DMG 1, then 2. And MM 1, then 2. Then MP 1 and 2. And so on.
If you are an older roleplayer like me, this does not bother you very much: you see the stuff in book 1 as the basis of where to start the game and book 2 and 3 as extra rules that you can use, maybe want to use.
As a new player, you have a problem. Do you need books 2 and 3? Can you play with just book 1? WTF should you buy?
Then the rules themselves: They are not easy to understand for a beginner. Easier than 3.x in my opinion, but not that easy for a complete beginner. Maybe there are too many options. As an older gamer, I have no problem ith this, but I play with unexperienced players and they sometimes do.
Last but not least, the split between 4E and 3.x. With 3.x you have the OGL. That was a good solution while there was only 3.x. But other companies could use that open liscence for ever for free. And because of this, WotC created their own competion for 4E. And Pathfinder thrives on that. That is why Pathfinder needs less errata: The system has been tested for 10 years. And Paizo was not responsible for the errata during that time, WotC was. So basically, concerning the rules system, Paizo is living off of the work that WotC has done. Which is fine, because that is what WotC has gotten itself into.
So now WotC is looking for new customers. And they see that new customers are confused by the many books with 2 and 3 in the title and the rules that are either 1. not that easy to understand or 2. too different from 3.x.
And that is why they created the Essentials line, which addresses the older roleplaying crowd by a "new" old-school flair (just check the old school cover art and the old school webpage design with the Deities and Demigods background). And the rules are easier for introductory play.
At the same time, though, they realize, that players nowadays use digital tools more often. And these people ask for digital tools that work. And they find that about 50.000 DDi subscribers probably make 6 million $ every year, without any printing costs.
And this is the direction where they are going: More internet services (which hopefully will work), less books but more digital content and books that make it clear that they are not core books, but offer options instead, in hardcover format.
And then WotC will see where to go from there. If people want to buy more fluff in book-form and crunch digitally, they will do that. If people still want MM3 in book-form, they will give them that.
Make no mistake: If WotC actually does deliver on digital tools, 4E will go through the roof. I am fully convinced that this is what people want.
So, to me, what they are doing now makes sense (in the meaning that I think I can follow what is going on).
Paizo does what they have always done: publish rpgs the old fashioned way, including the pdf.-format. And I do not mean that in a bad way. But it is not "going digital" the way we are seeing it with WotC.
Just my thoughts.