I can't say for certain, but I do believe I read a dev post that mentioned that you most likely will. That a bit like some of the other content that has been added since release, like tar, the new resources won't spawn normally in the already explored versions of their biomes. The mobs and entities like that may spawn, but any biome specific landmarks, resource nodes, etc, would likely not load into the explored but unfinished biomes on your map. Although from what I have heard there may be the option that unexplored versions of those biomes would still load the new resources once they are added, and I heard there's a mod that can make the new content spawn (though I imagine in a mods case, you might have to wait for that to update after the new content is released as well).