So you are suggesting that Microsoft will "throw away" an entire OS, and just implement features in Windows Mobile 9? RIM is not the hardware, they have a proprietary OS platform/push services and that is where the money is.
I believe Daring Fireball said it best:
http://daringfireball.net/linked/2008/10/10/rim-msft . It would mean they want to completely abandon Windows Mobile. Which has been a sub-par product from the start, there is a reason BlackBerry's are rooted within the corporate environment and Windows Mobile is not.