With regard to gliders, if Schleicher won't play ball, and Grob are out of the glider business, then the Glaser-Dirks could be a good alternative. The company is still actively manufacturing gliders, and when last buil, the DG-505, in its Orion form, was built in Slovenia, so should be rather more affordable than one built by German labour. For an order of 80 or so aircraft plus spares, they may consider restarting production.
The Air Cadets, if they are to carry on with conventional gliders need to adapt to the sites it will have access to in the future. The disused or unobstructed grass airfields which were plentiful in the 50s and 60s, are now the very ones the bean counters and housing ministers have in their sights, so will always be at risk, leading VGSs to have a nomadic existence.
A couple of points with regard to the RAFGSA, sure the numbers of servicemen actively involved in clubs throughout a given year may be smaller than in the past, but that is due to the reduced size of the RAF these days and the numbers of personnel deployed away from their home stations and overseas. Sure there are ex-service and civilian members, these are the people who provide the continuity and do maintenance tasks to ensure gliders and equipment are serviceable when serving personnel are available to come and fly.
Also, to suggest that several runway lights are broken per club per year is a gross exaggeration. I can recall two at our club in the ten years I've been a member. If other clubs are breaking more, their winch drivers and pilots need retraining.