Question: Any scoop on why Bones would need a new forensic anthropologist? Is something going to happen to Zack?

Answer: Sure sounds like it based on Fox's official episode description for the May 19 season finale: "When a human jawbone shows up at the Jeffersonian, Brennan and the team quickly realize that the Gormogon serial killer has struck again. In a shocking turn of events, an explosion in the lab sends Zack to the hospital; Gormogon's silver skeleton goes missing from the basement vault; and every Jeffersonian employee becomes a suspect, with the very real possibility that one of their very own may be working with the twisted and elusive serial killer."