Imagine a 5 man mission where 4 go in and do their thing as usual but the fifth steers off into a different direction raiding the ship where the loot is hidden.
When their are 5 tenno in your squad you no longer receive loot in 5 minute increments. Now it is entirely reliant on your fifth who is alone on the other ship.
The mission will act as a very large raid mission with loot hidden around the map that must be completed in stealth. Detection even once means you have to extract and each time you operative picks up an item from a cache he becomes weighted down. His movements become slower and slower eventually forcing him to walk. There will be drop offs that act as checkpoints where you can drop off the loot you have, saving it and allowing you to move at your original speed. When you have acquired all the loot in one map you fly to the next.
Although, enemies will begin to notice loot being taken and each consequent map visit will lead to increased numbers, higher levels, more cameras, etc. At higher levels they will disable your abilities.
These maps will also include puzzles, riddles, mazes, etc. You can keep going until you choose to extract or get detected. If you're detected you have a small window to escape and you may have to drop some of the loot you picked up so you can make it in time.
On the survival side the 4 operatives will have to cause as much damage as they can to keep the enemies distracted or else it will become much harder for the lone operative to acquire loot undetected. If these four fail at their objective a death squad will be sent to deal with the lone operative. Enemy levels and numbers will spike and they will periodically active emps, depleting energy and shields. Making it much harder for him to get out of there.
*Although a stealth overhaul is needed to really make this work. What do you think? Any suggestions?