No -- it's just communication and basic "hey, there is another person here with you." You still have separate worlds with separate elements and separate buildings. It's just letting you communicate.

from the patch notes it says they are the first steps to accomplish that.

I so do not envy the engineer who is pressured into hooking what is essentially two procedural generators, with the possibility for a alteration overlay together. If one mad guy alters a whole solar system into planet lava smileys..., how do you pack and transfer that information history on top of that, in real time...

This does work in Astroneer, but it was presumably designed for multiplayer from the beginning.

Why not just have one procedural generator for both players and send changes to and from a server where they both pull from?

The story goes something like this- they in fact have the same procedural generator. Both work upon the same key- thus mountains and everything is in the same place, provided they use the same hardware or the code is protected against floating point deviations.

The problem is- where do you begin and end with that? If a player can modify a world, basically, every change has to be distributed.. you have a sort of highres minecraft on your hands. Without originally being intended to be this. How do you sync it, if multiple players join and merge a universe?

I would have thought something along the lines of an acyclic graph ala git.