I saw that and was confused, I thought that would work out of the box with k8s since (I think?) it continually tries to keep scheduling pods; I must be wrong though.
If balancing gets implemented, am I correct that it would probably happen in k8s core?
I think I wouldn't assume that, myself; at least not after my stint in VietMWare (PTSD from a prior vSphere/vSAN experience)
We had VMTurbo/Turbonomic and VMWare's internal DRS that would sometimes compete against each other to decide where VMs should be scheduled.
You could handle balancing from inside of k8s core, or not. All you need is to evict the pod on the over-provisioned node, and to arrange for provisioning of the replacement node before the original pod is fully evicted. It should be the same for Kubernetes, if I had to guess.
If balancing gets implemented, am I correct that it would probably happen in k8s core?