Permit me to add my 2cents.
I'm a dedicated palmer/Target rifle shooter in Australia and I'm probably amongst the younger age brackets of our sport.
all the issues identified above in terms of declining demographics, participation rates and competition from other disciplines are faced by us in Australia and we are working overcoming them.
There is a real issues of attracting newbies and and young newbies in particular because it is a relatively specialised type of shooting with minimal application to hunting, the military and LE professions. The costs of starting are also expensive (specialised rifles, slings and jackets etc) and the learning curve can be steep. But When I first tried it 26, I was hooked though and drawn by the challenge it presented.
At our club we have successfully added about 6 new sling shooters to our ranks in the past 6-12mths (right across the demographic spectrum) and this is a reletively good result. I think we have been successful because we have sold it as a challenge and we have invested time in supporting and coaching our new shooters.
If you can differentiate the discipline and emphasise the unique challenges and rewards it offers you have a chance of capturing those who looking to do something a bit different. However, the cost and time commitments required are prohibitive in their own right and can usually deter or prevent those who might otherwise take up the sport. Especially guys and girls in the younger age bracket.
My perspective for what it's worth.
Cheers
Good post. Here in the US, newbies have the sink or swim experience. Very few new people get the coaching required.