The Maskling changes could be super fun, like having them guard the biomes with copper or limestone (or other rare resources), making it more difficult to get the higher resources. Makes having a military a requirement for the expansion of your empire.
These changes might also mean players will need to create new settlements and explore further then they might have before, and increase the importance of trading and your trade routes (protecting from masklings?).
Everything sounds great! Would you unlock adjacent regions through growth like population/wealth? Any plans for 1.5 to expand the number of current biomes?