i reckon the GBA might have done it had neither the DS or PSP come out, i mean it has managed 80 million even though it had a successor and a rival with a big name behind it when it was only 3 years old.
for DS passing ps2, i reckon christmas 2010
Wii i have no idea... i'm sure it will manage 80mil lifetime, but where it could get to might be a lot higher....ask me after christmas.