I am deeply concerned about this game. I liked Bioshock 2 a lot, so I don't think the series is doomed without Ken Levine, but it is definitely fighting an uphill battle under 2K. I don't see them giving a crap about retaining the thoughtful and thorough world-building and themes. Hearing open world is not tremendously inspiring either.
I don't know if I want to see Rapture again. It's probably my favourite location in gaming, but I think Infinite was ultimately correct to build a new place to experience for the first time. There's not much story left to explore or many secrets left to uncover. All that said, I think we are going back to Rapture. It's the easiest sell.