Maybe 2012 but not 2011
It would be hard on late comers and they are still making plenty of money now.
I am pretty sure there will be further little upgrades and that it will be backward compatible like the DS > DS Lite > DSi as that has won them alot of friends and customers.
2011 would mean they would have to start advertising next year but it would be hard to get anyone buying accessories for the Wii (like balance board, motion plus and the like) if people know there is a new one coming.
Don't forget there is always the replacement Xbox "just around the corner" according to analysts but I don't see it yet!