So I came up with this topic after playing around with Cornucupia (Adoomgod and ceno’s mod) for a while - now level 21 occultist.
So I have made a hybrid pet build on vanilla, a pyromancer with Blackwater cocktail, full hellhound (yes all modifiers maxed too) and points into flametouched, flashbang and the likes. It worked okay’ish, but the hound (dog) was to squishy and the emberclaw and infernal breath does not feel worth the investment.
I hope that crate will try to “fix” especially chaos/vitality pet hybrids so that we can have better builds with the covanent set or maybe witching hour 2handed gun.
I feel that the occultist mastery has come a long way since release (transmuter for solael’s+dreegs) but there is still some way to go.
So for pet hybrid builds right now all you can pick up is Dying god constellation and I feel this is sort of a shame. I wish they mixed in some pet damage/OA/resist on a few of the stars on some of the “less used” devotions like fetid pool, rhowan crown. Not so its a “pet only” devotion but a regular devotion with a little support for pets, just like the Empyrion constellation is right now.
The expansion is on the way and from what we have seen so far I think it does look promising, I especially like the the mythical will of bysmiel and I’m excited that I will be having +1 additional raven in addition to the cooldown ranged chton monsters that will deal tons of damage 
Fingers crossed! 