Although this approach is technically awesome, can't someone just modify existing noise cancellation technology with mics closer to the motors / props? It's a h

Although this approach is technically awesome, can't someone just modify existing noise cancellation technology with mics closer to the motors / props? It's a horrible hack, and nowhere near as elegant, but it may work quite well considering that no matter what signal is used for cancellation, it will be difficult to discriminate wanted / unwanted sounds in the cancelled frequencies.