As said, Murandy will provide a significant army and make sure that the Westlands aren't united. Besides that, I believe that Demandred controls most Dragonsworn Bands in all of the south, and possibly even Tarabon through its new King.

Just controlling Taim and his cronies would be a major letdown (and as said, basically still Rand rules the BT and most Asha'man), and is refuted by several clues in the books.

Moridin will lead the Trolloc armies from the Blight and attack from the north, while Demandred with Murandy and Taim with his cronies attack Andor and the other countries in the middle of the continent. At the same time most DF and Dragonsworn will probably also get the order to create chaos all over the Westlands, especially in the south.