It's the same billing as of the "Witchhunter-Tribute show" this month, on April 11th. I'm not there, since I've already tix for another festival on that date, with a killer billing of pure underground Thrash/Death/Heavy Metal bands from Germany.
Apart from Darkness & Protector I've seen them all before, Protector I'll see in December, leaves only Darkness, which is not so bad then.
But you're right. Even though Wacken is no pure thrash fest, people will go wherever they get the most value for their money and the best party! This year Wacken ain't worth a shitload of used TP. At least for me.
Keep it True alone can blast them away with their billings...