USB3 causes WiFi and Bluetooth interference
USB 30* Radio Frequency Interference on 24 GHz Devices
Perhaps not so bad if you've got well designed devices (i.e. with proper shielding and separation between the aerials and the connectors)... but almost certainly a nightmare if you've got users bringing cheap and nasty no-name tat.
Also bad enough for Apple to admit there might be an issue: Bluetooth: Unreliable wireless performance may occur when USB 3.0 external devices are close
Bluetooth Frequency Hopping - Interference
Bluetooth Frequency Hopping:
A Bluetooth access point operates on the 2.4GHz frequency band between 2.4 to 2.485GHz and taking advantage of this spread spectrum by a using a technique called adaptive frequency hopping.
As electronic devices are discovered operating within the vicinity of a Bluetooth access point, the adaptive technology switches or hops to an available unused frequency within the spectrum avoiding interference.
Frequency hopping is how Bluetooth works to maintain greater throughput as less packet resends are needed, and provides electronic interference protection for all Bluetooth devices operating in the piconet.
However, there are some who believe as I do that this "frequency hopping" behaviour stamps on other WiFi devices that are communicating in its proximity.