According to CNET , discussions with Nokia officials have unveiled that the N8 is planned to be the last Symbian based Nseries Device. All future high end device will be running on the Meego OS. It is expected that Symbian will now be relegated to the low-mid range handsets.
Quoting CNET :
According to the Nokia peeps we spoke to, the N8 will be the last N-series to run on Nokia’s Symbian platform; all N-Series from here on will run MeeGo. This leaves Symbian (in its current version 3 and the future version 4) on Nokia’s X- and E-series devices, with the budget-conscious C-series making use of the existing Series 40 platform. The N9 will be the first MeeGo device, but with the N8 shipping at the end of Q3 or early Q4 it’s hard to say whether the N9 will see the inside of phone stores before the end of the year.
Frankly speaking , this change has been long due as the Avkon UI of Symbian does not stand a chance against competing mobile operating systems. It is in Nokia’s best interest to promote MeeGo as the top end OS atleast till S^4 arrives later next year.