I think it would be very stupid of XBox to do it from the get-go.
Their current plans are selling the XBox for $100 less than what it costs to make it. In doing so, Microsoft hopes to sell more video games and make more money that way. If they were to open up the manufacturing of the console to third party companies, the price of the console would go up. The third party companies would be looking to make a proffit, so rather than selling the system for less than the manufacturing cost, the system would be sold for approximately $50 more than the manufacturing cost (that would be a $150 total turn-around in price).
I don't think that Microsoft would even considreing doing this until the cost of the components go down. I don't even think this would happen until two years after the release.
