They'll make it for wii.
It's just basically a PS2 one with slightly better graphics and a different control setup, maybe one or 2 more maps.
If they dont they're missing out a bit
No they wont. IW actually try and make something new instead of doing a cheap reskin like Treyarch, and they cant do that on Wii hardware. Treyarch have always made the games that go on all the systems, IW keep to the true next gen ones. But next November when Treyarch bring out WaW 2 you can get a cheap port of the MW2 engine (scaled down) with a WW2 skin.
Not to say WaW did nothing right. I'd like to see some of the better features in MW2, such as no more +2 for assists, toned down grenade damage, no 3xfrag, bayonets, extra classes, and selectable grenades. And of course, by FAR the best thing about WaW, Nazi Zombies.
IW should make MW2 not MW1.5. And also please make it glitch free. Any under-the-map glitches not fixed within 1 month, or assurances they know about them and are working to fix them, and I'm straight back to COD4.