Whoa, people go low end on Wii here...
Anyway, mine. I'll analyse a bit more than just put out the numbers.
Wii: 74M (minimum 70M, maximum 84M)
Reason:
I expect 45M sold ETY. ~ 29M shipped next year (just slightly upped production in Nov + Dec), and as sellthrough will remain, 74M on Wii. The lowest possible is really 70M. Highest? Honestly, I don't know.
Xbox 360: 36M (minimum 33M, maximum 39M)
I expect ~ 27M ETY. ~ 11M for the year 08 in total. Slight drop in 09, 20%. So ~ 9M next year.
Playstation 3: 29.5M (minimum 26M, maximum 33M)
Reason:
19.5M ETY. 10.5M for the year. Should stick on dead equal next year, 9.5-10M (within 10% of the 360), and thus 29-30M in total.
Nintendo Dual Screen: 125M (minimum 122M, maximum 132M)
Reason:
96M ETY. Should drop off slightly in the next year, despite DSi boosting sales. Still, 2007, 2008 and 2009 will all be virtually equal, within 15% of each other (~ 4.5M). I thus expect slightly less than 2008, but on par with 07. 29-30M for 09.
Playstation Portable: 56M (minimum 54M, maximum 59M)
Reason:
44M ETY. With 14M for the year. Should drop from year 3 to 4, and thus drop down to 11-12M.
Please debate about why my numbers are incorrect.