Who cares, the next system by MS, nor Sony will come before 2012, that's two years to go at the LEAST.
By this time PS3 will be leading the HD sales chart and Microsoft will be pushed to push out new technology so they don't fall back. I believe MS cannot afford to go second, Sony can as they are the dominant gaming brand. Wii doesn't impact either market, as Sony and MS really don't expect to get the casual gamers to their system. Sony more so doesn't care, as they sold more than 120M PS2's and they know how many people will eventually pick up a PS3. MS has been watching 360 sales go downhill, and watch the PS3's just climb year by year. If anyone feels the heat first to abandon their previous system, it will surely be Microsoft.