I am expecting DEP to be co-headliner this year along with at least one other Sumerian band considering Ash organizes it. The Faceless have been on it nearly every year so they are a possibility, Born of Osiris and After The Burial both will have new albums as well.
I would prefer Behemoth to Children of Bodom for the headliner but I think it will be one of these two. For old school bands I could see Napalm Death, Morbid Angel or Broken Hope (they are working on a new album) filling that role nicely.
04/05 - Kataklysm, Aborted
04/08 - Carcass, Gorguts, TBDM
04/23 - Behemoth
04/24 - Nile