I think that we will only see a new price cut on MS game on the end of 2009 when the CPU+GPU integration comes (probably a slim version).
For prices I think:
Elite $ 349
Pro $ 249
Arcade $ 179, mabe 169
No mater what Sony does, xbox 360 will always be cheaper
Ps3: Cell + Blu Ray + Bluetooth + Wi Fi + Memory Cards + PsN Costs