It sounds like something potentially Ninty might want to announce at E3 so that is the only reason I could think of it not being announced yet. Of course, if it isn't announced there, then obviously it isn't coming.
Really I don't see a necessity, as of now, for Activision to bring the game to Wii or any other platform than the 3 mentioned. However, they do run the risk that if they don't bring it over that they may never be able to establish a popular brand that is COD on the Wii userbase. With that they have potential to greatly increase sales but once again this is bonus not a necessity to break even.
I personally would think that Activision would want to try and stretch the brand. However, I'm not entirely sure Infinity War has the capabilities to develop a game on the Wii. They would probably have to outsource it to another developer... possibly Treyarch. So that's what I see as the main problem. Infinity Ward just may not have the abilities to put the game on the Wii while developing on the other platforms.
