I've been seeing this thread for a while, and have tried to ignore it, but it seems to keep popping to the top of the pile. So...
Could Pathfinder take D&D's place...of being the number one RPG game in the world?
Yes, I think it could. Though I also think it's just as likely that it won't.
But I think there's a much more important question:
Does it matter if it does?
Why is this so important to some that Pathfinder "beats" D&D? Why is it just as equally important to others that 4E remain on top? Will it really have any impact at all on the support that WotC and Paizo provide their games? Does anyone really believe that the survival of their game is in doubt? Or is this just a need to win that's so strong, people are willing to be rude, divisive, angry, insulting, and counterproductive to do so?
Then for both of those who wish to see their game "Win", I say this:
"A Pox on both your houses!"
4E is D&D. Pathfinder is D&D. Or more accurately, both are editions of D&D. No different than OD&D, BD&D, BECMI, AD&D, AD&D 2E, D&D 3E, and D&D 3.5E are D&D.
So what if Pathfinder starts outselling 4E...what difference does it make? Would it matter if OD&D started outselling both? Would it matter if AD&D made a resurgance as the most popular edition? They're all D&D, and they're all RPG's, and they're all FUN. 4E is a significantly different game from the other editions, and has become the preferred flavor for many players - and that's a good thing. They are playing the game they find fun. Just as the people playing Pathfinder are playing the game they find fun.
Unless someone is being forced to play a version or game that they don't want to (unlikely), then we can assume that most everyone is playing the game or edition that they like.
AND THAT'S ALL THAT MATTERS!
Why don't we all just give up this nonsense once and for all, and go play the game we like?
Then come back here and talk about playing the game we like...rather than talking about all the games we don't like.