I don't know, my feelings are mostly based on my experience. I left Pokemon 10 years ago with little interest, nothing at E3 or anywhere sparked an interest or let me know Pokemon was still alive until I both heard and saw X/Y gameplay along with screenshots.
To be pedantic, there's probably been only two main Pokemon title showcasings at E3: X/Y and FRLG.
I think pokemon is still very popular. Most people will know of it, and the sales are still darn solid (13+ million sales of BW alone, on par with the last few gens). If as Spino says it is the 2nd best selling videg game franchise, then it's big.
It's not Halo or whatever, it's not the sort of thing that 90% of people have played, and you'll never see people asking each other to come over to their house for a Pokémon session,
Halo hit 50 million sales late last year, so that's 11 years.
According to this list, the Game Freak main series games alone have sold 85 million copies in that amount of time. That's not counting any of the spinoffs which are numerous (and add at least 15-20 million more sales since 2002). So I'm fairly confident that Pokémon easily outsells Halo. =p It's also a far broader franchise - it has a still-watched anime and various spinoff games.
And yes, I have seen people ask others to play Pokemon. Heck, even at my uni you can see people play and talk about the game. Of course, these things vary region to region, but I don't think that it's any accident.
Granted, it is not as popular as it was back in the RBY days when the anime was fresh and Pokemon just had that wave of popularity to ride. Wikipedia does state RB had 23 million sales while GSC is also in the same ballpark, significantly higher than now. Different times, I suppose, and Pokémon was a new thing, not a series starting to near 20 years. But it's done well to maintain its current form imo.