Please list separate numbers. Let's assume for the question's sake that they both come out in November this year.
I'll say PS3 will be at about 79 million by that time. I think it will reach 100 million by the time it's taken off the market (PS2 sold about 33% after PS3 came out but PS3 has been out longer so I'll say it achieves just 25% of its sales as a legacy system). It still hasn't reached $200 which is crazy so it still has a lot of room to grow and many Americans I know (since I live in America and all) are waiting for it to get down there or lower to play all the awesome exclusives. Not to mention Sony sells in a lot of markets and is known for supporting their systems the longest (they said till 2015 at the least for PS3).
For 360 I see it reaching about 79 by the time November rolls around and I expect it to top out around 90 million. MS didn't support Xbox very much but a lot of Live titles will continue to come out since they don't require that much hardware and it still has another price cut or two eventually. It doesn't have the exclusives to get people to buy it as a second system however and the American market is saturated which is most likely to get a second because of the economy in Europe (and generally being a smaller market) and the hate for MS in Japan.
