I just thought that players being able to assasinate other players by the order of the Dark Brotherhood would be cool for you to be watching your back even more not just from the regular world pvpers but watching your back from contract killers would add much more fun to the game just like they did in Elder Scrolls V.

How it could work-

Players could go to the Brotherhood and ask for maybe and NPC assasination or a real player and if you choose a player assasination you can choose the difficulty based on the players alliance points maybe if you choose an apprentice contract you can get paid a small amount of money and so on going up on the difficulty.

Tracking the contract-

It would be very simple just like any other elder scrolls contract tracking just by telling you where they are and also add a tiny bit thing since of course it is an MMORPG now to just simply tell you when the player is on so you dont just chase a ghost.

No, this won't happen. They will now allow PVP anywhere else but Cyrodiil, and I wouldn't want them to.

They may allow Dark Brotherhood assassinations, but of NPC's.

It won't happen. PvP will only be in Cyrodiil. Now whether this will be implemented there, that'd be a different story...

Still, some people don't like PvP and don't want to be constantly on alert for these would-be assassins.

They COULD do it like SWG's bounties, but only relegated to Cyrodiil. So you get intel on a female Khajiit sorcerer who is currently in the area of Skingrad (the game knows there is one or several players matching that description in that area at that time). If you go and find one of them and kill them then you get a reward. Of course the target isn't warned about the hit so they can't just retreat to their own safe zones, but you'll still have to hurry...