I don't think it's a problem for young people standing up to perform. They do - there are a number of young performers around, and still more if you move off the "folk" scene and look more widely at the "acoustic" scene.
The bigger problem, it seems to me, is that very few young people (performers or others) are actually taking up the organisation or set-up of what we call a folk club. It's been said before, but when I started performing the clubs were run by people who were only slightly older than I was at the time. That seems to be still true, mostly (although there are some organisers who are a decade or so younger than me). And where young people are running a venue, it's not necessarily called (or behaving as)a folk club.
So, taking Tom's comments on board, we've either got to persuade more youngsters to get involved in the running of the folk venues or persuade ourselves to look at a wider definition of what a folk club could be. For example I discovered fairly recently that in Cardiff there are several venues that might well book me, but as a folkie I'd assumed they were venues dealing with a whole different genre of music. (Still haven't secured that booking, btw, but watch this space!)   We may, as performers and lovers of the music, need to adapt to survive - but that's a normal development, isn't it?

Anne