In a theoretical universe where modes aren't used as a crutch to keep odd PvP feel, strange PvE orientation on important game mechanics, anemic security response that will do little against gankers, monetary consequences (like rebuy or bounties) being really oddly balanced, important combat balance numerics like typical TTK's being basically randomized... and so on... basically, in a theoretical universe where Elite: Dangerous is designed to work as a game with proper PvP, in that game I would be all for a separate Open Only server. Singleplayers can then stay in a snapshot of that server where they can play in the same universe, but obviously not affect things like BGS directly, that's obviously ridicilous.
As it is right now? Eeeeh... will there actually be something enjoyable? Will the player threat actually add something?
I think at some point the idea that this game would be designed with PvP in mind faded away... I feel like things like EDD tried to work out how nonconsensual PvP would work in a good way... look up a typical video of high-level PvP to see what the current state is.
If I had a chance to go back to my old account, I would definitely want to try out 'open only' server. Just to see a galaxy with BGS factions that make sense in some way would be worth it. I don't think I would want to stay, but it would be an interesting experiment. And maybe I am wrong and there will be interesting gameplay?