The loss of AMN SHOULD not be as big of a nerf as it’s actually going to be, but some talents are bugged and are not receiving any bonus from our mastery unless we take it, even if, logically, they should be gaining our full mastery.
The Hunt and Sigil of Spite are both Chaos damage by default now, but both are NOT affected by our mastery at all unless we take AMN, which definitely sounds like a bug holdover from when they were nature and arcane damage respectfully.
If they make Demonsurge, Immolation Aura, and Collective Anguish (to keep up with the other two capstones) Chaos Damage, and fix the bugs with The Hunt and Sigil of Spite, then losing AMN wont be the gutting it is currently slated to be.