I know nothing about any leaks but do have a theory about what we will see this Sunday.
D&D are huge on foreshadowing.
They've established Cersei is going to rely on the Iron Bank to likely employ the Golden Company mercenaries.
They've established that Tyrion has got the religious in Essos to back Danny via the Red Witches.
They have Melissandra back in Essos and promising to return.
Then...