Discussions like this have been going on for over a year now. The core question of this thread is, do we need an Open PvE mode? The simple answer is no, we don't because we already have it, its called a private group. There are already very large player policed private groups dedicated to PvE style of game play. The need is already being fulfilled.
I am one of those people what would prefer there to be just one game mode, Open. I am however positive that it would never work with the current implementation. With no real consequences for being a hat, hats come out of the void like a bad plague. Its just the nature of the internet. And who but an hat wants to play on a server filled with hats. Elite Dangerous is a PvP game, but its not PvP focused and its the first, if I am not mistaken, in this series to even offer PvP.
IN truth they should remove open and leave it Solo and Groups, there are enough private groups that can give Dedicated PVP style of gameplay that a mode is unnecessary as the need has already been fulfilled by Private Groups. And when the leader of the PVP private group leaves the game or something happens to them.. another player just start up the group again and re invite everyone.. then they can have their PVP all they want and leave the rest of us alone.