A lot of folks just can't get over the fact that the windsurfing fad ended years ago, but many of us that started 20-25 years ago are still religiously involved, hence the growing age of windsurfers. Water sports in general don't always attract the masses, because the majority of folks just don't want to recreate in the water. Also, there is a lot of competition for those that do with other popular water sports, like surfing, kiting, SUP, waterskiing/wakeboarding, kayaking, boating and jetskis (I have to admit that I would have little grief if jetskis vanished from the face of the earth).
Is windsurfing going to grow? Sure, but folks will also leave the sport too, so the overall numbers aren't multiplying markedly. Windsurfing is a highly specialized sport, even if we're looking at a relatively simple longboard kit. The fun in windsurfing requires wind and water, and that's not always available in a convenient way that fits folks' schedules. As a result, the sport requires a significant amount of dedication and tenacity, to include an ability to tolerate a certain amount of frustration and disappointment. Add to that the fact that windsurfing requires some wallet to keep updated and viable across a broad spectrum of conditions. Where are you going to store the stuff when it's not in use?
I could go on and on about this topic, but I think we all recognize the realities in the sport. Frankly, I can accept the fact that windsurfing is not going to be super huge, but I can readily appreciate its esoteric qualities, and I'm particularly glad that some others feel similarly.
Quite honestly, I have no fear that windsurfing will die.