Currently Wii has 70 1million+ sellers, PS3 has 48 and XB360 88.
Nintendo has an overwhelming presence amongst Wii top sellers, MS has a strong presence, with the absolute best seller too, amongst XB360 ones, but it leaves a lot of room to 3rd parties, Sony has a strong presence, but it leaves even more room to 3rd parties. I don't know whether it's intentional, but this is the situation, and the overall market is growing.
So sloppiest or worst managed developers will kick the bucket, because the competition is stronger than ever, but crabby people hoping for most 3rd parties to die will be disappointed.