If you lose Foo Fighters then it's a big job to try to fill those shoes as a headliner. Not everyone's cup of tea but a proper "big hitter" when it comes to ticket sales.
I haven't seen anyone else on the road next summer who will shift tickets. Muse are decent and I wouldn't mind seeing them again, but I can't see them selling out. I simply cannot think of anyone else who is knocking about who could shift Pearl Jam volumes of tickets.