Good way to divide it further I would have thought.
Literally placing another mode that avoids being together and all. There's two of those already, I like all the modes, but I don't think we really need another.
Also, open PVE implies you'd need to have some way to stop damage from other players but not NPCs, this would require a bunch of code edits. I'd imagine it would actually be none trivial to do. Add to that, the fact that you'd have this weird thing where ships become invicible bumper cars! and things get slightly... odd?
I also feel like squadrons might help here a bit, as, squadrons could create their own private groups, providing an easy way to communicate, and set up a large private group, allowing you to play with others that you trust.
Looks like a multiplayer feature might help out solo/pg folks too.