I don't really see people buying a 360 BECAUSE it has Natal, or a PS3 BECAUSE it has the Eyewand. People will have their console preference and if the games that support the mo-co tech are compelling enough people will buy the tech. Those who truly have no preference of either console will decide on price and available games. I really don't think they'll be particularly swayed by a peripheral device.
Natal and Eyewand both have 2 significant drawbacks compared to Wiimote/motion+ that I think will see these technologies have a fairly modest adoption rate: Firstly, if some predictions are to be believed, the 360 has been sold to nearly 50% of those people who are going to buy a 360, likewise PS3 has been sold to somewhere between 35 and 50% of all the people who are going to buy a PS3. By the time Eyewand releases PS3 will have sold to an even greater proportion of it's total market, and if 360 is much later than mid next year it will be getting up to 60% of it's eventual total market. The necessary pick-up rate from existing console owners will need to be massive if either tech is going to have the impact some people think it will. Conversely the Wiimote is in every single household that owns a Wii, motion+ has been released and I think this will give people a guide as to the maximum likely uptake of any mo-co tech Sony and MS introduce. Secondly there is a huge library of games out there for both PS3 and 360 that cannot support mo-co, and , because of the first point, after MS and Sony release their mo-co there will still be a large number of new games that release without [compulsory] mo-co. There is simply no way developers are going to severely restrict their potential market by making mo-co an essential part of every game they produce. Again Wii doesn't have this problem because everyone has a mo-co device so mo-co can be an essential feature of every game. Games requiring motion+ will sell less than games that can use the standard Wiimote, simply because 40-something million people don't have motion+.
There is a Wii peripheral we can look that has been out much longer than the motion + to give us what I would say is the maximum possible market penetration for Natal and Eyewand in this generation: the Wii balance board. Wii Fit has sold something around 21 million, this is less than 50% of the Wii install base. The game itself is selling at about 50% of the Wii itself. This is an absolute phenomenon for a non-bundled game, it puts any of the most popular hardocre gaming franchises on any console to shame. Natal and Eyewand will be lucky to do half of what Wii Fit has managed.
My gut feeling is that Natal and Eyewand will not sell systems in any great quantity, and they will only be modestly successful as peripherals this gen. If either company is fully committed to mo-co as the future gaming then they will show it by embedding this tech in every console sold in the next console generation. But that'll make the launch price of both consoles rather hefty, or they will have to wear bigger losses with each unit sold. Wii did it better once again by making their mo-co non-camera based. It might limit the scope of the mo-co slightly, but it made for much easier implementation and adoption by gamers.
On the OP's predictions: the numbers could be plausible, or they may be totally unrealistic. For me to make my own judgement on the quality of the prediction I'd have to see your analysis for how you came to those numbers. On the face of it the numbers seem like they could be fairly accurate, though it would appear they are on the generous side for PS3.
To those who claim ODST is going to move 360s: How exactly? It's an expansion pack for Halo 3. Surely 99% those who are going to get ODST already have Halo 3. I think ODST might increase 360 sales by a couple of percent for 1 or 2 weeks, but not enough to have a significant effect on relative sales between PS3, 360 and Wii.
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