The current industrial automation landscape faces considerable challenges due to the increasing growth of Industrial Internet of Things (IIoT) devices, cloud services, IT/OT convergence, along with evolving hyper-scaler technologies such as Kubernetes and distributed computing. This paper provides an in-depth review of the existing ISA-95 Model and its current role in supporting manufacturing systems and their interactions. Additionally, it examines how emerging technologies are impacting the security, design, and management of Operational Technology (OT) networks. As existing perimeter-based models, such as ISA-95, are pushed to their limits, the concepts of Zero Trust architectures, and policy based or software-defined networks are being explored as the next generation of OT network design. This paper aims to provide a high-level introduction to the concepts and disruptive technologies, and introduce the potential implementation risks and challenges of these principles within traditional IT/OT converged solutions.