To preface this, I will say flat out.. I am of the opinion that combat in GW2 is based around the dynamics of 5v5 spvp. And for proof I point at the conditions and pet systems. Both clearly work well in pvp environments when dealing with other players, but when translated to pve the break down fast, and rather dramatically at times.
SO: In pvp, you face all level 80 characters wearing full exotic gear loadouts with rather exacting stat breakdowns. In pve you are facing enemies who vary in levels, difficulty, scale, and have presumably atypical stat allocations. All those weird things in pve means dealing with calculations…multipliers for short. Ranger pets, and others though not slaved to them as Rangers are, are spvp npcs. Thus not able to deal properly with all those wild multipliers that pve is going to throw at them, either at a mechanical level of how they are treated scale wise (as npcs) or the brains to dodge outta the red circle.
The Fix: In pve only, have Ranger (and possibly other) pets assigned their own special mob rank. Thus almost forcing the game to apply those missing pve multipliers, and potentially allowing a custom level of scaling based on the instance, or area of an instance the pet/it’s owner is in. To clarify, trash mobs have a portrait, Vet mobs have a bronze (I assume) circle, elite have silver, champions gold with swords and legendary get purple and spiky. Pets would have their own unique one, and whether visible or not, a similar pve mob rank.
How I see it working: This will allow the pets to be power-fixed to specific areas, In a dungeon for example, the most common mob ranks are Elite, thus it would make sense to me for a pet to have it’s health scaled as such, equal to the elite mobs of the instance. This is where the pet’s own unique mob rank would come into play, having an elite pet would be OP, but having its own custom rank would allow it’s damage to be set to different scales, or even left to their current scales as much as possible. While I know it can’t be this easy, I think it would be worth the pains to hammer out in the long term. So the pet would do about as much damage as they do now, but would have it’s health and armor type calculations done equal to the mobs of the area.
How would this work in FotM? Where you will likely start facing mobs of level 81+ Vet status? Same as dungeons, let the area mobs scale effect pet health/defense multipliers, and then keep the damage at whatever it’s current scale is.
Open world? Well, this is where it can get tricky and the possibility of some down scaling skullduggery appears. The only place I think this could be easily exploited is if the ranger stands in higher level areas of the zone and sends in their buffed pet to kill lower level mobs across the boundary. There are leash mechanics that could come into play around these, though most are clear enough of mobs anyway (fixed soon after release iirc). But for open world, the option is there to scale the pets with the mobs dynamically, meaning only when in combat, in the area of an event, scaled with mobs spawned by the event as in dungeons/instances, or the scaling could even be left as is in the open world by having an “I’m in open world content” flag tell the system to turn on the currently existing system.
tl,dr: pets are given a unique mob rank (trash, vet, elite, champ…pet), and this system is used to effect pve mob scaling by zone/area to give the pet the mechanical survival advantages that pve mobs get but allowing their damage calculations to remain about where they are now.