Such an irritating topic that gets repeated constantly by people who didn't do any research into what this game is. There is no point in forcing people to play in a universe that they don't want to. They won't help you, they won't be a challenge, they won't add anything except an extra hollow square occationally when super cruising. There are so many solar systems just in inhabited space, that it's entirely possible to fly for hours without seeing anyone. It's the same way in EVE and in it everyone plays in the same universe. The only thing that forcing people into online will do is alienate the people who want to play solo.
I used to think that making people choose one or the other or just having online was the best idea but then I realized that this game isn't a competition, other players don't interfere with your "progress" any more than npcs do, there are no corporations or player factions, etc. It's basically a single player game where random people happen to be real sometimes.
Have you even played this game?
there are factions and corporation just not player owned but they are player controled and large groups change the systems in a way that the open mode players just cant tend with. there for if poeple want to play solo they should have their own universe to change and people who play private group should have the same and the people who play open should be able to have thier own universe as well, none of thease three should have an effect on one another at all.