Different take on Pets
It’s too late for something like this. The pet mechanic already exists in it’s current form and it would be a complete abandonment of the class to move in this direction.
That would require a change to ranger utilities, traits, and just about everything else. It’s an interesting idea for a pet based class, but I don’t think they are going to completely scrap a class mechanic. Improving it is one thing, but swapping it out for something else is different.
Its been brought up before, making pets less like NPCs and more like pure support. And I hate it every time its brought up. I rolled a Ranger because I want a companion who fights beside me, not a mobile sprite / turret that floats around and fires off a special attack every once in a while.
The idea itself isn’t terrible, it would be an interesting mechanic in and of itself. If they introduced a Druid class with mechanics as described in the OP which used animal spirits instead of actual animals (they could still be gotten from juveniles, but instead of charming the actual animal you “commune with its spirit” or something) I’d totally play that class. They could even split off some of Ranger’s current skills like spirits to that class and give Ranger new ones, let Druids handle the “one with nature and commanding nature’s power” theme and just make Rangers more huntsman simply familiar and comfortable in the wild.
But I don’t want to have them simply change Ranger pet mechanics altogether to something like this.
Pets fading in and out of existence to accomplish a 5-second task would break my suspension of disbelief, I think. That sort of mechanic only works with the Warhorn call-bird ability due to the nature of the summons (and even that is really odd-looking when you, say, call down the birds on a giant-sized MOB and they appear gigantic as well… looks silly). No other ground-based pet would look believable. At least, to me.