Metal Gear Solid 4, as of now, is still not lost. But there are strong rumors that the 360 will get a Metal Gear Solid game. I actually heard this game might be shown during this year's E3.
Concerning the wii - It doesn't appeal to me either, and many people I know who have one have started to go back to their playstation 2's and 360's. In my personal experience, only the strong nintendo fans have continued to make it their main system.