I'd still like it done "in universe". You don't need separate modes when you have so much space. You just need different, variable environments within that space. To be honest you can partially achieve this by simply moving away from busy areas, but that also eliminates friendly player interactions. Which is why I'd like to see some heavily policed, peacefull sections of the bubble.
Make secure and anarchic systems actually actually mean something. If you turn up with a big bounty in a high secure system, or commit an assault in one, it should be death-on-a-stick. However, in Anarchy no effect at all. Weaker systems somewhere between the two.
To be honest. I think Solo only exists because offline became non viable. It's essentially offline, with the universe data online rather than on the hard drive. Perfectly sensible hybrid of both offline and online play, allowing the massive universe whilst also maintaining privacy.
Open is probably what it was always intended to be (multiplayer), which would be why it doesn't protect players that much.
People can tweak their routers to avoid appearing in an instance with other players. People could go into busy/anarchic/losec systems and only ever meet NPCs.
One reason why I suspect Frontier won't be pushing the game in this direction.
Cheers, Phos.