i doubt nintendo will drop their price for a while since their selling out. the point of a price drop is to create demand which they obviously don't need.
the 360 will probaly have a price drop soonish but not as much as your suggesting. i'd guess they'll wait until a big event to maximize the effect like the release of GTA IV.
sony is taking such a loss on the ps3 that i doubt they'll be able to afford another price drop for a long long time. probably no price drop at all this next year imo.