Developement effort for that would be huge, not trivial. TSW players asked that question to Lead Systems Designer in one of their regular Ask a Dev things. Here was the Question and Answer:
How difficult would it be to duplicate the zones for nightmare level folks? QL 10.2+ Solomon Island for example
To duplicate an existing zone for nightmare level players isn't as simple as it would seem, unfortunately. On the Systems side of things, we'd have to make new copies of every enemy with new stats and new abilities where necessary. In addition, we'd need to update their loot tables with new rewards and we'd probably have to consider updating the mission rewards as well. However, the main bulk of the work would have to come from our Gameplay Designers. When making a copy of a zone, all of the hooks and scripts and patrol paths and AI points will all break and need to be manually re-linked and in some cases, remade. In essence, they would need to remake and retest every quest in the zone to make sure everything is working properly. On top of that, they'd have to update any necessary scripts and enemy spawns to reference the new monsters that we had created.