The big news is
Battle brother are
Eldar + Dark Eldar
Chaos Space Marines + Chaos Demons
All Imperial Forces
Armies Allied with their own Codex

Allies of convenience
Imperial and Eldar
Chaos Space Marines with Necrons or Orks
Tau and Eldar or Necrons

Tau and Space Marines are now desperate allies

distrusted allies has gone.

You can find the full table here. https://lh5.googleusercontent.com/-71myQ7gRwaM/U3vXkbzQEII/AAAAAAAAASM/WOA_ZRfas5E/s640/blogger-image-2122138276.jpg

7th Edition is going to be a lot more fun.