1 hour ago, Roland said:
The inclusion of a new biome would most certainly require a restart and not work with current saves so it couldn't be something that was pushed out as an update. They almost certainly would have to make it a DLC giving gamers the choice to manually download it and have to start a new world. That doesn't mean that it has to be a paid DLC. They could do just as you said and make it a free download with some accompanying thematic outfits and skins that they charge for. However, I doubt something major like a new biome would simply be pushed out to everyone as an automatic update.
I don't think this is correct. It would be no different from downloading a mod that adds a new biome. If your current save doesn't have that biome, the new biome in the mod wouldn't have any effect. Since the existing save doesn't use the new biome, it wouldn't affect anything to have it available. It would only be an issue if a biome that is used in a save was either removed or changed.
The only way I could see it being an issue is if they wanted to update Navesgane or existing pregen maps to use the new biome. That would need to be done through a DLC because of needing a new game on those maps.