Nah man, this is my game, air gap systems aren’t really a thing for anything non-military anymore. Companies want a real-time view into their production for making business decisions.
There are ways to secure your control systems network properly without a full airgap with proper boundary controls between the various layers of your Purdue model as well as fully separate Active Directories just to make a start.
Its actually an entire independent cybersecurity specialisation for OT networks. For anyone who is interested I would recommend Hacking Exposed Industrial Control Systems: ICS and SCADA Security Secrets & Solutions by Clint Bodungen its a fantastic read and very easy to follow.
Now the concept of air gapping still exists in this architecture, its designed to be able to “Island” which is where you break the connection between your corporate and OT networks when an incident has occurred on the corporate side essentially creating an airgap.