If they do put in trading, I think there should be a limit to how many times you can trade either a day or weekly, and you can only trade items of the same rarity and type. For example, I got a legendary sniper, a friend has a legendary shotgun, we can trade, but if the shotgun was rare or lower we can't trade, so it's always a fair trade. For exotics, I think we shouldn't be allowed to trade them, but that's just me.