The future progressive Training package document that's been available since April shows that gold Wing courses are "Reserved for cadets wishing to pursue Flight Staff Cadets (FSC) service"
Cadets don't "join" a VGS as before they remain "owned" by their normal squadron and don't show up against the establishment which is limited but they are still FSCs. There may occasionally in the future be a point where a VGS establishment is full when an FSC reaches 18, with no post to go to in adult service with the VGS that there maybe a tough call on manning for the OC.