Let's say the year is 2018.
DS - 200 Million
PSP- 95 Million
Wii- 150 Million
Xbox 360- 66 Million
PS3- 65.9 Million
I think the DS will remain strong during the 3DS years and sales will continue to be high until 2015 when we will see a large dip in sales.
The PSP will have a couple more strong years a head of itself and make it to at least 95, and possibly 100.
The Wii will have a strong 2011 and 2012 and around 2013 Nintendo will make the Wii more available in Middle Eastern Countries, Africa, Asia and South America. The Wii will also be very cheap by this time and it will have strong other sales but slowing down Japan and America sales. By 2018 the Wii will be virtually dead in the West but it will have some small sales from Others markets.
The Xbox 360 will continue with strong west sales until around 2012,2013 when sales will dip because of the new console. Because it failed to grab others market it will linger around with decent sales up until 2015-2018 when Microsoft will discontinue it.
The PS3 will likely have a longer life span. But it's American and Japanese market will slowly fade away by 2013-2014. The PS3 will be kept alive by it's Others market for a few years. But because the Wii is much cheaper and Nintendo can get more out into developing markets, it will keep PS3 sales in Others below Wii sales. By 2016-2018 the PS3 will be off the market and possibly surpassing Xbox 360 sales, but if not the gap will be less then 500k.