Greetings Undead Labs!
I believe that adding challenging Expeditions to dynamic and dense urban areas would add variety and more endgame content.
High Risk. High Reward.
Urban Expeditions would also satisfy the communities craving for explorable urban environments without the difficulty of having to tackle a project quite as large as Lifeline.
Expeditions could also (maybe) be used as an alternate method of awarding prestige points.
These areas could be used as "Dungeons" and could be linear (alleys/inside large structures) much like the tutorial military camp or could be set up as open world areas that simply span a few city blocks.
These Dungeons could help further explore and expand the Lore and Story of the game.
Each expedition could have varying difficulty.
The more difficult the expidition = the better the loot.
I believe that 3 or more "Dungeons" would be best to help the expeditions feel diverse and would also help maintain the suspension of disbelief that the city is large with many different areas.
Each Expedition should drop the player into a randomly selected "Dungeon".
More Dungeons could be added later in development.
The player would be able to utilize these urban excursions to scavenge for the best loot at a high risk or undertake special Expadition style missions.
The amount of loot that is recovered could be balanced by how much the player can hold in their bags and/or how much gear can fit on the insertion/extraction vehicle (Sasquatch's Helicopter perhaps?)
I know this would be a massive project but I hope I at least caught your attention :)