That would be interesting but I can't really see it happening. Most of the rumors about the Wii 2 so far suggest a late 2012 release date and I think at least one of MS or Sony would release another console in 2013. I would say the only way I can see it happening is if the Wii 2 launches this year and Nintendo completely drop support for the Wii. I would say the best chance the Wii has of losing a region is in Japan and I think PS3 would need to be around for a long time, and maybe get a couple of big exlcusive games like a Monster Hunter or Dragon Quest to have a chance at completely clsoing the five million gap.
I do agree that the final sales in each region will be a lot closer than they are now.