You do realize that 21.8m would put it at like 106.5m, :P?
Your prediction could be easily blown, though, :P - Nintendo may do even less for software than this year, Vitality Sensor may be 2012 and Wii may not cut price, :P.
If all three of your conditions do take place (which I doubt, xD), then I'd say you're lowballing it.
“These are my principles; if you don’t like them, I have others.” – Groucho Marx