Simon,
you pose a good question and I think that some of the answers are more obscure than going to watch a demonstrator for the evening.
There is a growing movement for the 'Men's Sheds Association', this started in Australia, and came to us via Ireland. It offers a place for men (although I believe not exclusively) to go and continue to use their knowledge of a lifetime. There they can help others learn a new skill, help others repair something (also branching out as Repair Cafe's), or just make something. Not only in wood, but metal and electronics and all the other engineering skills they have.
Our Woodturning Night are an older but probably just another aspect of this sort of organisation.
It has been noted that once a man retires, he tends to lose contact with many of his work colleagues, and his social circle becomes worryingly small, it enables them to have a more active social like, meet new people and pass on their skills.
I'll also add that it has saved lives, I can name at least 2 people I know that are still with us because it was noticed by someone at the club that they were 'ill' (for want of a better word), and a visit to the doctor was advised. I also believe this is a recognised benefit of these sorts of organisation in Australia.
How we draw in the next generation, that is a whole different question. Again our sort of clubs are for the older person, there are younger members but these are generally a rarity. As people get to the point in their life when they are looking to take up a hobby and decide on (or to try) woodturning, we need to find them and introduce them to the club system. How we do that is harder. We have tried advertising, flyers on car windscreens, public demonstrations etc., but even then the club numbers only are fairly stable. As we lose one we gain one.
I do teach some young people the skills as part of their DoE award scheme, knowing that they will walk away but hopeful that a few will return to it in the future when they need a hobby. One does come to a club with me and is a junior member of the AWGB. I also understand that some of his classmates are a little jealous of the things he sometimes take into school to show off as a 'Look what I've made now'.