Sorry about the thread bump, but just got some info on this. It will be a new hotel tower. It is NOT an extension of the Swan & Dolphin. That is basically all I know.
But according to @marni1971 , the land is owned by the Swolphin owners. So... what is meant by "not an extension of the Swan & Dolphin?" That it's not going to be called Swan and/or Dolphin? That's it's not going to be a Westin or a Sheraton but some other Marriott brand? That Marriott isn't involved at all?