Please remember that these are rumors although are pretty tight as far as Chaos and Dark Angels being in the starter set now.
via Beasts of War
Chaos Powered Armoured Marines will be included, as well as the new Dreadnought (or renamed dreadnought).
On the Dark Angel side of things, Belial is in there, leading the assumption that on the Dark Angels side there might not be much powered armour. Instead it could very easily be two units of Deathwing Terminators and even some fancy new Ravenwing Jetbikes.