I've been going to Comic-Con for 14 years now, and the one thing that's been constant throughout that time is that people complain that "it's not about comics anymore".
There are too many booths about TV, movies, video games, toys, t-shirts, role-playing games, etc, they say. It's gotten away from the purity it had 5 years ago (it's perpetually 5 years ago; a rolling date of when it was still what people wanted it to be). While I can't dispute that comics only make up a percentage of what is shown at Comic-Con, I have to disagree with the gloomy, slippery-slope predictions people make.
Comic-Con is always going to be about comics. It may be silly that everything else's connection to it is through comics' typical genres (sci-fi movies, animated TV shows, superhero video games), but it's an honest, organic evolution, and it's certainly a shared fan base. It just wouldn't happen otherwise. I mean, there was a ton of promotional stuff at CCI 08 about the TV show "The Office", which is about as remote a property as you could possibly have, and yet it fit in perfectly at the con.
Comic-Con also has the biggest Artists' Alley/Small Press section of any convention I've been to, and nearly all of those people is a comic book artist. The Artists' Alley is juried and tightly monitored, so there are almost always popular creators, and almost never empty booths. It's not a flashy area of the show, but it's the best floor-space-to-interesting person ratio in the room.
And the strongest point I could make that this diversification has helped, rather than hurt, comics is this:
Once a year, there is one event that is the undisputed center of the universe for all Western pop culture attended by over 125,000 people. No one dares miss it, and movie, video game, and comic studios and publishers will wait six months to announce new projects there, to great fanfare. And what's this giant omni-media celebration called? Why, it's called COMIC-CON.
That sort of branding of comics in the mainstream media as the wellspring from which all other fun, awesome, exciting pop culture comes more than offsets, in my mind, any perceived loss of comics purity. And if you don't buy that, buddy, I've got four words for you: MoCCA, Heroes Con, SPX, and APE.
Oh, and of course, The Minnesota FallCon.