In this age of NFC, WiFi, BT, RFID, and everything in between, I am really not sure that the elite security concept of “air-gapping” is even meaningful or useful anymore.

Just because a measure is less useful doesn't mean it is useless. There is always a compromise between convince and security and in this case one would have to do even more screening (less convince) for the same security level. Even if airgaps like before increases effort needed for exfiltration.