Do Unity have plans for Extended Position Based Dynamics?
Incredibly accurate and cool physics
I don’t think this depends on Unity but on the provider(s) of the physics engine, in this case PhysX, Box2D, and maybe Havok in the future.
This might be implemented using kinematic Rigidbodies. These would provide the collision detection and contact points, and the physics implementation could resolve for position and orientation.
PBD is a different approach to physics compared to what available now. Actually, the current cloth component of Unity uses a PBD implementation, which runs in parallel to the traditional physic engine, but both are provided by NVIDIA. With XPBD, the inventors of PBD seem to have extended the usage of PBD to work with rigidbody physics, whereas it was mainly used to simulate fabric or fluids before.
Additionally Unity has UnityPhysics that can implement this. Theoretically 
UnityPhysics involves using a different game engine (ECS), and everything around that is still in preview/pre-alpha with uncertain future, so I’m not considering it.