I don't think there is really any evidence that this has had any effect in the past. It was confirmed last year that the 360 would have a price drop and it didn't have a noticeable effect on sales. Japan is another beast, 360 sales went below 1k before getting a huge boost, ps3 sales also slowly died to 3k before getting a big boost from bundles (not lower price but better value).
currently playing: Skyward Sword, Mario Sunshine, Xenoblade Chronicles X