The devs had said before that as long as you do not visit the biome, or that part of the map, it won't actually generate yet. So if you do not explore to farther islands until the update is out you will be safe.

BUT I don't know if they've made very many major changes to all the other biomes. It's possible they will be tweaking things and adding others that are requirements for new recipes so you might as well prepare to make a whole new world anyway.