I believe that adding in Greenland could be a good idea, could do wonders for infighting among the Viking factions. You could have Greenland rebel, and to ensure that int would be invaded by the vikings simply utilise the Massalia trick. In fact the Massalia trick should be used on the Englisc, and Norman coasts.

As for new foundland, that would just be silly, I mean imagine the amount of time it would take to cross the sea. Plus we'd have to add a new faction, the Ameri-Indians.