There are two main factors at play here:
1/ How aggressive do Ninty want to be? Are they HAPPY to sell "just" 20m (12 * 1.8m approx) Wiis per year, for the next 3-5-10 years? They may well be - this gives them time to develop and sell software after all.
2/ "Hard" manufacturing limits: its difficult to explain to people (in a short period of time), but it gets to a point where its IMPOSSIBLE to manufacture Wiis faster. Not harder, not more expensive - but IMPOSSIBLE.
The core chips that come from IBM (CPU/GPU) have "hard" manufacturing limits. That is, the machines that make them - simply cannot make them any faster than they are currently being made.
For Ninty to *significantly* increase manufacturing levels would require a MASSIVE investment, and several years (if not longer) - i.e. potentially build their own factories. I doubt this is something they would ever do - rather just hunt down for more manufacturing partners, and slowly increase the output from all their factories.
I'm guessing they manage to upp their output a little next year (maybe up to around 2m/year, maybe a little more) - but not much more than this.
This results in around 23m-25m for the fiscal year ('08-'09), and assuming they are around 23m-25m sold by March '08 (their forecast) - results in around 50m total sold by March '09, or 45-47m sold by end of Xmas '08.
...
Ninty would have to pull a REAL rabbit out of the bag to increase production to around 3m/m, needed to get to the 60m level. And I don't see it happening - for now anyway.
Gesta Non Verba
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