4. Rappelling & Abseiling
As we've seen in the gameplay trailer and a couple of screenshots, there will be elements of this in the single player, but whether you will be able to do this anywhere or only in certain scripted missions remains unknown. I would love them to take it one step further and have this as an online feature, where you would be able to transport people by helicopter over a building and have them rappel onto the roof. This would add a new sense of freedom, and allow you to tackle online heists in a whole new way. It would also make missions fun to replay, as you could first do it on the ground without the help of air vehicles and then try it again, infiltrating from the roof. Even though you might not want to constantly replay missions due to there being around 700 of them at launch, it's nice to have this sort of freedom.