Price is one of the factors that influences how well a system sells but it is not the only one, and it is far from the most important factor. How changing the price will impact each system is largely dependant on how this new price relates to the value of the system in the consumer's eyes; if you bundled another game and an additional Wiimote and Nunchuck with the Wii for $199 it could easily be seen as a far better value to many consumers than a $199 PS3.
The general health of the system is another important factor. People generally buy a system for the games that are readily available as well as the games that are going to be released in the future. If one (or several) equal or better game(s) are started as a game is released for a system you could say that it is generally healthy, in contrast if exclusive games are replaced by multiplatform games and (many) multiplatform games leave your system then you could say that the system is generally unhealthy. This "Healthy" of a system is related to hardware sales, the system that is selling better generally has an easier time attracting new software development to it; in this generation it should be interesting to see how the cost of development will factor in.
