Of course this idea is heavily influenced by the popular series ".hack//", however I think there's a few things that can be improved, like for instance a completely open world, not just instances. It'd probably be difficult to have a completely open world, but the immersion would be held pretty steadily with the lack of loading screens. To make it even better would be to take something from a popular MMO called "M.U. Online" and another called "Mabinogi." That would of course be the reborn system, where there's a high max level, but you can reborn yourself to get a total and current level. It'd just be a reset of level and you keep your stats. I think this would keep people playing for a long time(as those games have shown.)
The Virtual Reality aspect could come from the Oculus Rift. It'd be a subscription based game, and there would be no text chat, only voice chat. So it'd require a microphone for communication, and as in some games currently, your character's mouth would move when you talk in-game.
There might be 2 servers, or 1. If there was 2 then I'd recommend a role-play server and a normal server. The game should also have pure open PvP, where you can kill other characters even when in towns, but if any guards could hear they'd investigate and if they saw then they'd attack the characters. They could also put out bounties on the people that killed them, so that bounty hunters can go out and kill them for rewards. There could be several bosses in dungeons... and this is where it becomes hard to keep it pure open-world: Other people can still loot from you and other people can assassinate you while you're fighting in a dungeon. I like that there's such an option, but it obviously has some problems with it. This could easily be fixed with dungeon instances but it'd lower the level of immersion with loading screens.
That's enough of my idea so far, I'd enjoy reading your thoughts and opinions and also would like it if anyone could pick up this idea and develop it, but of course the brainstorming isn't over until everyone comes to the same conclusion.
Thanks for reading.
-Death