I'm not interested in an offline single-player version. Meeting the occasional real player ingame, and seeing friends, would keep Vanadiel alive. Being the only living soul in Vanadiel would just kill the happy memories for me, even worse than the off button.

I am totally interested in keeping my character data.

I am totally interested in any kind of Museum Server / embalming system, for loyal fans to meet and chat and enjoy Vanadiel minus version updates. Either run by SE, or run by another group. I suspect that any kind of single server for loyal fans, would bring out the best in players, and the atmosphere would be really fun because everyone would only be there because they are so devoted to the core FFXI game.