Terraform already does a three way reconciliation at plan/apply time. It checks declared state (your code), known state (your statefile), and current state (api calls to your providers).
If you want to see this, just make a terraform apply. After it completes, go change something directly in your cloud provider and run another plan. The top section of your plan will highlight the changes that Terraform found remotely that don't match existing state.
So all this would do is remove known state, so you could do a 2-way reconciliation instead of a 3-way reconciliation. You would compare current-state with declared state. This is how Kubernetes works. But to be fair, Kubernetes actually works in a slightly more controlled environment than Terraform.
If you want to see this, just make a terraform apply. After it completes, go change something directly in your cloud provider and run another plan. The top section of your plan will highlight the changes that Terraform found remotely that don't match existing state.
So all this would do is remove known state, so you could do a 2-way reconciliation instead of a 3-way reconciliation. You would compare current-state with declared state. This is how Kubernetes works. But to be fair, Kubernetes actually works in a slightly more controlled environment than Terraform.