flagship on 21 July 2008
Because MS has already lost billions on the xbox franchise and would at least like to make some of that back.
Also as the number of systems increases market share becomes less and less of a factor because a lot of people aren't buying more than a game or 2 a year. Currently the 360 has a very high attachment rate and major games can easily sell 1 million + units, so an extra million units on the market probably won't make a huge difference in software success.
