If I'm not mistaken, even long after the War of the Ring, there are still three Istari (Maiar) left... Did Tolkien have any plans - they are very powerful, and I suppose the most powerful beings who remain in Middle-Earth, aren't they? Did he give any clues in his letters?
If Sauron was a Maiar and went astray, one of these Istari could create similar terror like him?
If Sauron was a Maiar and went astray, one of these Istari could create similar terror like him?

