PS3:
Low end: 18 million
Actual expectations: 26 million
High end: 35 million
That's right, 35 million is the absolute highest I can imagine PS3 selling. It will not reach a mass market price for at least 5 years, at which point the generation will be all but over. Its lineup of killer apps (GT, GTA, FF, MGS) is roughly comparable to the cream of N64s lineup, except that it relies on third parties and includes a non-exclusive. I can't see it doing less than 10 million in America, 3 million in Japan, and 5 million in Europe, though, and realistically I expect it to do 13/4/9.
360:
Low end: 24 million
Actual expectations: 32 million
High end: 40 million
With sales diminishing in America, things are looking down for 360. It can no longer be argued that a price cut will help the console compete with Wii, it needs a price cut just to get back to XBox levels. With the current sub-XBox level of sales, that leaves 360 at about XBox's total even with an extra 2 years on the market, due to the sales slowdown 2nd and 3rd place consoles experience late in the cycle. However, I expect Halo and GTA are going to provide a major boost for the console, and think the differences between Wii and 360 as opposed to PS2 and XB will help 360 maintain higher long term sales than previous 2nd place consoles, which would help the console move well beyond XBox.
Wii:
Low end: 80 million
Actual expectations: 150 million
High end: 40 gazillion??
Nintendo would really have to blow it to sell less than 100 million. (I think videogames have reached a point where the winning console is ALWAYS going to sell 100 million.) I see them selling over 30 million in Japan, over 60 million in America, and over 50 million in Europe/others--basically a large incremental audience growth in some ways similar to PSone. But if they screw over Europe completely, doubt their American success and focus on Japan too much, and then only reach PS2-levels in Japan instead of drafting off of DS, they could only reach maybe 80 million. There's always the possibility Wii is bigger than anyone can imagine, too, thus my 40 gazillion top end.
"[Our former customers] are unable to find software which they WANT to play."
"The way to solve this problem lies in how to communicate what kind of games [they CAN play]."
Satoru Iwata, Nintendo President. Only slightly paraphrased.