What is the state of the UE4 physics engine in 2018 and where is it headed in the future (Apeiron)?

I hope so too. Although I will keep using PhysX to setup BP (with nativization I will need or I would have to rewrite in pure C++ for performance reasons as needed) static meshes to destructibles runtime swapping indeed having Chaos destructibles instead along with Niagara particles would mean a huge performance boost even because the new APIs can use the GPU and aren’t limited to CPU. Anyway I still need quite some time to figure out how to properly write and make batch scripting with Python for creating destructibles and I will need to do many tests to ensure the fastest swapping algorithm I can write from the various example codes and studying UE APIs as needed. But as soon as I will have completed all that I will start assembling the level maps with world composition for my first game and I hope that later on removing PhysX destructibles by replacing them with Chaos ones could be very easy to do. I will probably avoid adding particles effects to the PhysX version anyway because if Chaos will be production ready in the next 12 months then I might be able to avoid being forced to release the game with PhysX at all.
Your Cloudscape Seasons I bought some time ago I will add to the maps when I will have almost completed everything so by then I might need your help to configure it properly.