They should turn the USCIS into a CM parking structure. Just like I think they should turn that CM lot next to M&Fs into a parking structure too.
As for CM parking on Manchester, no way, as the traffic flow plans would have too many vehicles entering/exiting onto Manchester/Clementine. Now, adding onto the Main Pumbaa structure and sending more cars there would allow more CM parking at the Katella Lot, and that is a good benefit. Disney keeps its shuttle costs down by eliminating one stop.
As for the North extension of the M&F lot, the Bakery building is an issue, as the costs for a small structure wouldn't pencil out as cost effective.
The best place to build a CM structure currently is the Ball Road Lot. The land wouldn't be used for anything else, has decent freeway access, and wouldn't impact anything. Simple Rectangular lot, so construction should be fairly easy.