I agree, I now think an Open-PvE mode is the only way forward after what we've read of the start of DW2. I used to be against this because disabling damage seems artificial and I preferred C&P and meaningful system security, but I now see that that's futile. If FD are watching this I hope that they'll take away the same lesson.
It could be done without much development effort. All damage is already tagged by source so that bounties, C&P, mission counts and "You were killed by..." messages can work. All that would be needed would be a final check that damage is from an allowed source before applying it.
It was a good try. Other games have also tried to avoid simple flagging, but finally been driven to having a PvE mode. In every case its been a successful and popular change. I hope FD are working on it (but I wouldn't expect them to say yet if they were).
The Open PvE mode means a separate game. Since we share the same BGS, such separation will cut the opportunity of FD to implement cross platform and player’s controlled assets affected in open only. Not sure if such things will ever happen, but they will have more options to react according to players attitude to keep the game alive. In such case, the Open PvE wills double the expenses for game maintenance.