Star Wars: The Force Awakens had to come to San Diego Comic-Con. After all, the original movie came to the con way back in the 70s for promotion, one of the earliest (maybe the earliest) films to do so. There's a tradition. You gotta have Star Wars.
That doesn't mean you gotta have new Star Wars footage. Fans who are considering camping out overnight to get into Hall H and see the big Lucasfilm presentation should be warned: EW is reporting that there will be no new trailer and no new footage screened this weekend. There will be some kind of behind-the-scenes EPK style thing, which I am sure will include some easter eggs and some hints that can be picked apart, but anyone hoping for actual new movie footage is out of luck.
It's a bummer, but it makes some sense, as Disney's D23 fan convention is coming up in August. That's probably why Marvel is skipping as well - why give all your goodies away at someone else's party when you're throwing a party of your own? This all but guarantees that the next trailer will drop at D23.
What should you expect from the Lucasfilm presentation? I wouldn't be surprised if we got some new info on characters, and maybe even images of them - perhaps a look at Andy Serkis' Supreme Leader Snoke, fully realized. And it's very plausible that Rogue One, which is rumored to already be shooting, could reveal its whole cast.
I'm actually surprised by this news, as I thought for sure that JJ Abrams would give the fans something cool and unique. Withholders gotta whithhold, I guess.