The 2009 to 2010 drop for Wii was pretty substantial worldwide, but the level of Wiis sold was still higher than, among others:

1) The PSP peak (16m)

2) The X360 or PS3 peak (at least to date these are 14m / 12m)

3) The NES peak (13m)

4) The SNES or Genesis peak (not sure - probably 11m / 8m?)

5) Every year of PS2 sales save for the best two (22m in 2002, 20m in 2005), every year of PS1 save for the best year (20m).

Carl is right, the 2009 price cut was still doing good work in early 2010, and sales settled at a decent enough level in 2010, with a major rebound late on the retailer discounts (Wii was $150 for a while at a couple places anyway without an official price cut) and software.

I doubt its ending as soon as you think, probably fall 2012 at the earliest, they may show off the next console at E3, but probably just the box itslef, not the games until next year