With the new DH archetype, its clear pets are still a playstyle element that the devs want to support. However, most players find that pets are too difficult to manage in meaningful difficulties because they just dont survive well. There's been some attempts to improve that with gear and pet enhancements, but those are limited in effect because there's only so much that can be done to make pets competitive on their own.

So a better solution might be to make them not fully independent from their owners. I think a shared health mechanic might greatly improve the utility of pet classes - both damage and healing partially pass through from one to the other, so a pet becomes more of an extension of the player's character.

I would say there should be some absorption mechanic, so its not just pure 50/50...maybe like damage done to one is reduced by 50%, but then 40% of that damage is applied to the other. That provides some innate defensive utility for pet use. Healing would pass through at an increased rate, maybe 100% for the target and 50% of it is passed through. Both would be affected by the target's mitigation/amplification before being passed. Damage would be further mitigated by your defensive stats when passed to the player, so that a squishy pet doesnt become a vulnerability for a tankier player.

I think that would turn pets into valuable tanks/damage sponges and let them better serve their intended role, without needing nearly as much babysitting in combat.