The concept of physical license plates is completely outdated anyway.
Can you explain? As a cheap and pretty much failure-free means of visually broadcasting the identity of a vehicle, they seem pretty irreplaceable. Anything requiring electronics is much more prone to failure. Even airplanes have their call signs written clearly somewhere on their body.
Now for GA aircraft the call sign used is usually their registration no. (not sure it's mandatory for them, but that's what's used). For commercial, it's related to their flight number.