I asked a few questions around and apparently Maiden is headlining Donington. I don't know if the UK tour is happening at all, but maybe it will later in the year? Bruce Dickinson also quite confirmed this during his Swansea show by saying "see you in a muddy field soon".
If this is true for real what a waste for Maiden fans.
Maiden, Slipknot and Sleep Token it is. Hopefully the rest of the bands will surprise us, or Download 25 will go down as one of the most boring edition ever.