I remember last year with the leaked PS3 slim production photos coming out in March or so, yet the Slim itself came out in September and that was supply constrained throughout the holidays. Sony had at least 9 months worth of production and still couldn't come out with enough consoles in the end to satisfy all the demand from one quarter of sales. Thats my precedent.
Now the Xbox 360 is coming out in June, but I don't believe that Microsoft are any more prepared for this launch than Sony was in September last year with their respective revision. To sell another 6M consoles from here or so, they will need to produce an average of 300,000 consoles a week to satisfy demand. Thats a pretty tough ask, but I suspect its doable. Thats more than they have released onto the market thus far if you go by the average rate the revision consoles are selling at. I don't think they could supply 10M or 8M consoles.
Kinect is coming out in November, however compared to Move or the Wiimote its probably taking quite a few more steps to produce. It is a far more complicated product than Move because it comes with 10 bit camera sensors which AFAIK aren't produced in high numbers already and it contains a mechanical motor which means that every Kinect accessory will also require much more testing before it leaves the factory. I don't think they will have produced enough of these to satisfy demand even at the higher price point unless Kinect totally bombs. However I will assume it'll sell a few million or so based off reasonably strong pre-orders and Microsofts big marketing push.
If they were to price the base console lower or the price of the Kinect camera itself lower as either one would probably lower the cost of the bundled Arcade it would increase demand and I believe they couldn't sell any more even if they wanted to. So coming in at a lower price would probably be counter-productive in terms of overall revenue and therefore would lower the profit they could attain. I also believe that the fact that the Arcade is coming with a 4GB (32Gbit) flash module also supports this theory, as they are currently the highest capacity flash chips in mass production and therefore the most expensive. If they had intended a price cut they would have used a much cheaper 1GB chip most likely.
