General idea:
When players enter the survival mode lobby, they get to chose the option for Expert Survival Mode. The game mode is identical to the original survival but with harder conditions and enemies. Players would have to be more focused and scavange the map more. It will give a greater risk but in return give a very realistic gameplay and a much bigger challenge.

Expert mode features:
* Hunters spawn random
Players are 'chased' by hunters during the entire survival run. They either spawn after a random time or at random locations. Hunters will drop 2 high-end items and 1 consumable when killed. Player can encounter up to 3 hunters when not extracting.

* enchanted hunger
Players suffer more from hunger. Hunger kicks in faster than original survival. When the player is hungry, the disorient status is always active. Cause naturally you can't function perfectly when hungry. Also health drops twice as fast.

* enchanted thirst
Player suffers more from thirst. Thirst kicks in faster than original survival. When the player is thirsty, the player cannot sprint. Also skills are disrupted. Health drops twice as fast.

* enchanted cold
The player body temperature drops at the same rate as original survival. However the freezing-status is more punishing. Health drops twice as fast.

* ammunition
When player reloads, the remaining bullets from the original magazine are lost. (The same handicapt from the original underground)

* Landmarks
Landmarks outside dz will also have a named boss. And more NPC's. Named bosses will drop 2 high-end items and 1 consumable.

* legendary npc's
Npc's in the dz are legendary LMB.


Rewards:
Each completed expert survival will always reward an additional expert cache which will drop the following:
* 1 exotic or gear set item
* 1 exotic or classified gear set item


I think this could bring survival back to life in the game. As for now, I believe the original surival is quite easy if you know the how to. And it's quite under-rewarding when looking at the time invested. I believe this is an update which does not take an extreme lot of development. And I think with the right tweaks, this could be turned into one of the, if not the most, challenging feature the end-game has to offer.