By next week, Danielle will have passed Bermuda, so your cruise won't be impacted.
This week's cruises may be affected depending on the direction the storm takes. NCL has a Weather Alert button on its Web site (ncl.com) with updates. So far, no itinerary changes. Again, this is for Bermuda cruises departing this week (yesterday and this weekend).
As to the general question concerning where ships would go, it would also depend upon the path of the storm, along with Passenger Services Act requirements. A rerouted Bermuda cruise typically goes to Halifax and New England or south to the Bahamas. This is a rare occurrence, though. It's more common for a ship to alter its arrival and/or departure times from Bermuda.