Amateurs are the lifeblood of all other motorsports.
They pay to race as their hobby. Their entry fees put money into the sport. It supports venues and industry suppliers.
There is none of this in speedway. Club racing, well run, can provide a fulfilling day's racing for competitors of all levels. Entry fees, not ticket sales, sustain the clubs. Young riders get an opportunity to practice and develop. Older riders get a chance of competing on their own terms. A few, very few, make it to a level where they make money, or at least break even.
If I was a youngster, I'd rather race motocross where I get more track time. All Britain's top racers in other disciplines started off in club racing, it's where talent develops.
The whole concept of developing speedway as a professional product for the fans is flawed in my opinion. Develop the product for the riders, a mass of riders. Give them a product that's appealing, that they'd rather do instead of motocross, enduro or banger racing, and let that keep the clubs and venues alive. Venues who feel that they can offer a spectator led offering are, of course, welcome to do so.
I can't see a future for speedway, but having a stable base at the bottom of the sport is critical. How can speedway attract new riders when there is essentially nowhere to practice?
BTW, speedway is not the only sport in this position. Consumers have more choice now. Going to speedway was a big night out for me in the early 80s. Now I have so many other things wanting my dollar, and they almost always win.