(What If?) Enemies of the 4th Age

[Snorri Swifthammer]

So I've been idly speculating on a What If? scenario for Middle-Earth.

I've been thinking what if a new Enemy arose in the 4th age to challenge the Free Peoples. Now I'm trying to think of a leader for these new forces of evil and have come up with two ideas.

1. Mouth of Sauron - He is still alive (in the books) and at least has some influence in Mordor. Perhaps he could rally the remains of the forces of Mordor and strike against Gondor in revenge of his master.

2. Alatar and Pallando - (Sorry alatar!) Both these wizards disappeared somewhere into the East. We know the Easterlings allied with the forces of Mordor. What if A&P where corrputed by their power and set themselves up as Wizard-Kings of the East? They could certainly cause alot of trouble.

So what other forces of evil are still moving in the 4th age? Who would you think could pull together an army? Remember this is just idle speculation, I'm not staying to any sort of canon ideas of Middle-Earth, just a fun thought experiment.