The Conduit had Wii speak and 12 player online and it worked, why not MW:R?
The Conduit runs on a completely different engine, and has closed in, mostly corridor type maps. The engine was designed to take advantage of Wii Speak. Having said this, the device still shows its flaws as a FPS chat device in that many players experience lag when using the device, as well as poor quality audio including echoing and excessive amounts of background noise from the game itself. A headset option is the only realistic option for a FPS on the Wii, however until Nintendo or another company introduces one, it is not likely a good solution to the online chat problem will be solved.