Tbh I don't think they will be back at BS for a while. I was surprised they played last year. By my reckoning they have played BS/BOA and related gigs five times and I think if they were booked again there would be complaints that BS is just sticking to the same formula and the same bands!
I was told last night that Angra are 90% confirmed for Wacken, so you could have them at Bloodstock seeing as they don't have a UK date and they'll be around at the time