Come on now, you have to have seen that the Wii has been losing steam as far as new releases on the console goes. I mean really, there hasn't been a whole lot of really great titles within the past year on the Wii, and the VC releases have been slim to none. I think Nintendo's ready to move onto the next console.
If anything has more time on the market, it's the PS3 and 360. PS3 really took a hit with the whole online fiasco, and a new console too soon afterwards might cause a dip in sales due to people who got turned off by the way Sony handled that new situation. Plus PSN and XBLA have only been getting better and better compared to Wii VC.