I say end of 08 or at the latest march of 09 (depending on pricing). The VAST majority of consoles are moved at a price point of 200 dollars or less, that's the sweet spot. The Wii will obviously be the first to reach that pricepoint. If it can keep a good momentum in 08 with solid 1st part effort (brawl, Mariokart, ect maybe starfox or pikmin by christmas season), and some good 3rd party support (Monster hunter, Final Fantasy Crystal Bearers, ect) just enough to keep people looking their way then by mid 08 it could even be possible by a slim margin.
Really it's most dependant on the PS3. Sony is slashing about like a cornered animal right now, but in 08 that animal will get some claws. It may very well be too late by then for it too pick up too much steam, but even if it does well it's still going to only delay the inevitable. At this point I just don't see it increasing it's sales by %400 while the wii with it's incredible momentum just hits a wall.
Pricing will be everything, and once the already popular wii hits the mainstream price of 200 or less, it's sales will increase even more, supply shortages won't last forever and once Nintendo gets more of them out there they will be eaten up.
So early 09 if Sony gets some momentum, 6-9 months into 08 if Sony continues to flounder.
