It's called hostile PVE.
So this is an idea that has always intrigued me, but perhaps further down the line in Destiny's development, hostile PVE can be implemented.
The whole idea is to allow players to kill other players in PVE. Players may choose to PK due to limited resources (something Bungie should add as well) or factional affiliation.
Reputation could be given for each player of an opposing faction that you kill and bounties could be established.
Hostile PVE would lead to Player Threat Level (PTL). A player's PTL would be measured by the amount of other players killed within PVE areas. PVE areas would be broken up into security sectors - green, yellow, and red with green being a safe zone which is no PK'ing allowed or you take a massive hit to your PTL, yellow being a "heads up, it's dangerous here," and red being a free for all kill em up PVE zone. A player's bounty would be tied with their PTL with the more PK kills, the higher their glimmer and reputation payout for their death.
I think this would make patrol a lot more fun and put a different spin on PVP instead of your typical lobby shooter. Imagine having to collect resources for your faction but knowing you need to travel with a group and watch your back because some hostile Dead Orbit sympathizers has you in their crosshairs.
Questions, concerns, complaints, comments?