I think the PSP will stall around 30m. Maybe it reaches 40, but probably 35.
360 I think will stall around 25M. Not too bad for selling in 2 of 3 markets (trying in all 3). Maybe they make 30M but I cant see much more than that.
I think after this Xmas we should have a good idea.
I don't think the 360 can do better than the PSP. Not with low sales in Japan. That will keep some of the killer games off of their system, or prevent them from getting certain exclusives.