You're probably right. However Maynard into Black Keys on Monday might constitute a solid 4th headliner by committee. (in my books anyway)
See Gramma? I told you that would be awesome! ;D I mentioned them in another thread and most didn't think they'd fit the vibe. They would be more likely than Tool since Maynard isn't into whoring them right now.
Also, For the record, I loved 13th Step. "The Noose" is arguably the best APC song ever.