The idea of adding Essos has been discussed but I think in the long-run the team is more likely to focus on polishing the game after v1.0 rather than adding a whole other continent. This is because the dynamic of the game is based upon Westeros, hence the title of the mod, and adding a continent would completely change this dynamic. As such it's more something we see as sub-moddable, for the time-being at least.