Here's a fun idea which I'm sure would take no work at all to implement: escalating PowerPlay NPC threat levels which scale upward in solo and group mode with every PowerPlay achievement made in Open.
How it would work: every time someone in Open shoots down an NPC, pirates cargo, or collects and drops off cargo, it would slightly increase the threat level of the NPCs in that same area for the corresponding Power. NPCs would scale in quantity, aggressiveness, loadout, and piloting skill, all the way up to eventually being ATR-equivalent ships but without the magic weapons.
Open Mode would always remain at the default level of NPC AI.
It would be a way to connect the "parallel universes" without locking anyone out of anything or violating the Sanctity Of The Modes, while also ensuring that highly contested areas are areas of consequence for anyone.
Think of it like a game of split screen vs Tetris: when you clear out a line of blocks it dumps a bunch of them into your opponent's play area.
I think you have a fantastic idea. It definitely addresses the issue I was making about a more logical format in which we are all operating.
GIVE THIS GUY A BEER!