In order to add to the challenge in PvP, and in order to add some spice to PvE, Anet should introduce some truly rare consumables, and base them on the same type of system as the dye system.
Example: Player kills mob, gets loot, and in the loot is a rare-consumable container. They can then A) sell it on trading post, or
open it and see what it reveals, and then choose to either use or sell the result.
The consumables should be combat related, and need to be truly rare. Not “rare” as in yellow named, but rare as in they drop about as much as precursors do right now.
On top of that, the resulting consumable needs to be ridiculously powerful, but the more powerful it is, the more drawbacks it has.
An example would be a consumable that has an AoE effect which makes everyone in range take only 10% incoming damage for 30seconds, but they are rooted, and cannot move for the duration, nor can they cancel it.
Yes, this would be terrible to go up against in WvW, but the idea is that such a potion is so rare that it would sell for 5k gold on the marketplace or so.
Other consumables could have devastating effects but cost the user their life (go straight to dead, do not pass go, do not collect 200karma).
Again, the balance against their strength is their drawbacks and their rarity/cost.