[Santosh83]

It might no longer be as simple as at a glance in a world with ubiquitous wireless. You'd have to take special care to disable or disconnect all wireless chips in your system. And that might be hard for laptops and impossible in lower form factors.

[alasdair_]

Even without radios, there are lots of different ways to get data in and out of an airgapped system. Examples include everything from sound (especially ultrasonic beacons etc. as these are used for cellphone marketing today) to more esoteric stuff like flashing the LEDs in a specific pattern or even changing the cpu temperature to specific levels.

[fulldecent]

Or how about the AM radio transmitter that is built into all x86 hardware - https://github.com/fulldecent/system-bus-radio