I think it would be a big mistake to start EWR as a lo-cost operation. It would be for point to point traffic only whereas what is needed is a service offering connections throughout the US (e.g. CO).
With Emirates looking like they could make a success of the new Dubai route it would bring NCL to the attention of the big full service airlines and as a previous contributor pointed out, it is important to keep NCL as a mixed airline operation. Otherwise we run the risk of losing everything if the lo-cost bubble should ever burst.