Glenn,
The unique asset of United States is that she is a US flagged ship, thus able to call on one US port directly from another. NCL stated that their plan for United States was to rebuild her for intra Hawaii or California-Hawaii service. Although they were able to "reflag" one of their other ships, that was seemingly a one time event, so any expansion of cruises within the US, including Hawaii, will depend on rebuilding United States. It's still not a certainty, but smart marketing would emphasize the ship's history and speed records to build a following. It could be a very profitable venture. I hope a similar case could be made for France/Norway in Europe, even as a static hotel/museum.
Regards,
Charles