Good thread indeed.
200m has always been a little out of reach, I don't think any console ever will reach that number. Unless we end up with only only one console sometime in the future. It's just too much. 150m would have been my guess at the start of this generation. Too bad Nintendo dropped it quite suddenly and now it still hasn't reached 100m yet.
How many years did it take PS2 to reach 100m? Maybe Wii can still take that record. I think Wii is just about able to touch it this holiday, getting to like 100.1m or something.
I agree with some others here that it still should be able to get to 110m-120m if Nintendo plays their cards right. They should cut the price to $/€99 soon and start supporting other regions, basically do it PS2-style. Maybe even go to $/€79 in the distant future. This also goes for the DS, which should be able to get to 170m-180m this way. If there's one thing Sony did right, it's handling the PS2's death.