I could do without Clapton. Saw him a few years ago and he obviously did not give a shit. Definitely going through the motions. He's been pretty open in interviews about how much he hates the road these days.
Jan. 26th-30th MMJ's One Big Holiday
Feb. 15th Jeff Tweedy
April 18th Twista
May 2nd-4th Beale St. Music Fest
June 11th-16th Bonnaroo
June 29th Summerfest - Outkast
August 16th Andrew Bird and the hands of glory
Sept. 4th-7th Lockn' Fest
Nov. 19th Mavis Staples celebrating 75 years
Jan. 23rd Sam Smith
Jan. 29th-Feb. 6th MMJ's One Big Holiday
I may be in the minority here, but I think the most likely legacy headliner next year is U2. They're working on a double LP, planning a new tour, have expressed interest in American festivals and are on AC's wishlist.