User blog comment:Gandalf1801/Question/@comment-4828844-20150330020826

Sometime after Aragorn's death, a new shadow comes. A new character, Herumor (whose name literally means "Dark Lord"), becomes a leader of a cult which worshipped Melkor and Sauron. Saelon was possibly a member of this cult as well.

Gandalf becoming a Vala seems unlikely to me. Hierarchy in Valinor does not work that way, I guess. There were only fifteen of them, Melkor included.

The Blue Wizards were given specific tasks in the East. They might have been informed about Sauron's downfall.