It most likely will be provided with a connection box that will accept that metal plug. In the photos I see a cable end that looks like it would connect onto a remote head kit faceplate, so that is how it will connect to the RF deck. This is how a previous Hand-held head, the KCH-16 hooked up. It had a KRK-11 interface box it utilized.
HOWEVER... The model pictured above (KCH-21H if I can read the label correctly) seems to have a single color LCD screen, and not the full-color style of the NX-5000 series, so I'm not sure this is destined for the 5000's... Maybe for the NX-x00 series since those are not color? If it was a full-color LCD, it would look black when turned off, not grayish-silver as it appears in the photos.