According to chapter 292's spoilers, the boss or a sub-boss will make an appearance. Please, let's talk about all predictions and facts about the upcoming boss in this thread, so it doesn't fill up the latest chapter discussions.
Most people on ST think the upcoming boss is going to be David. I wouldn't personally mind if that's true, but I'm starting to think its something bigger. My preferred choice would be Zeus.
A worldwide mission of this caliber deserves a boss like that.