I honestly liked an idea I saw about open-world PvP. There would be a planet you can choose to go to where damage to other players is enabled. I would also like to add players could be aligned on this planet based on chosen factions. Dead Orbit players, Future War Cult players, New Monarchy players, and Vanguard/Crucible/non-aligned players would all be separate "teams." Class items would be unchangeable until you return to orbit.