Lets take a closer look at the possibilities. First off, I know that we have had power armour, non power armour, power armour releases, but I do not believe that this is a hardfast rule for GW in their releases. If it is, just swap out chaos legions for March and Tau for June. Please remember that is quite a bit of speculation beyond that Necrons should be here in November.
November 2011- Necrons
June- Chaos Legions
August- 6th edition
Starter being Chaos vs (Eldar or Black Templar) Most say Black Templar
November- Black Templar