I wouldn't mind one little bit if the story is structured like Lensmen, with several layers of villains that have to be discovered.

Admittedly, this is less likely in the wizarding world-- the population is much lower than in a universe with multiple inhabited galaxies.

On the gripping hand, it would be really cool if Quirrel/Voldemort were a claw on a finger of a conspiracy of evil alien wizards. Presumably, Cthulhu is part of the middle layer.