The writing was on the wall with regards to the state of hardcore wii third party titles, but with the recent bombings of both the conduit and madworld I think you can kiss any genuine exclusive third party hardcore support goodbye.
It doesn't make sense and it never made sense. The reason Wii's are selling the units they are isn't because of games like Call of Duty, it's because of games like Mario Kart, Wii Sports, and Wii Fit. These are the games that Wii owners purchased the system for. It makes sense, then, that this demographic doesn't care whatsoever about some no-name first person new IP shooter.
Conversely, Halo pretty much established the entire Xbox brand, and so it's of no surprise that the main titles on the platform cater to that audience while casual games have tended to bomb. It's the completely reverse situation.