User blog comment:FairyRaven/Fairy Tail Chapters 338, 339, 340: Review and Commentary/@comment-1359322-20130705132226/@comment-7418318-20130705151626

I'm not sure.

I think the main antagonists of the next arc will be Tartaros, with Zeref just doing some stuff in the background for now and he'll only come out into the open in the 2nd or even 3rd arc.

I wonder if Oracion Seis will join with Tartaros, Zeref or get their own arc.