In one photo, Booth and Brennan "try to piece together the exact location and identity of the sniper who fired at The Gravedigger." So we know the Gravedigger will be fired at, but will she be the one who dies? (Not that we would miss her, of course. She nearly took out Brennan, Booth, and Hodgins.)
Another still from Bones shows Sweets with blood on him, but fear not, Lance Lovers! He was close to the action, but he's just fine.
As for the Gravedigger, she did swear that "this wasn't over" after she was convicted in Season 5's "The Beginning in the End." So even if she does die, there could be a chance she worked with a partner. Or could she get a stay of execution at the last minute? Anything is possible.