I have been into airguns from pre-teens and love them to bits. They're my life and the main thing that keep me sane. Licensing wouldn't diminish my love for them, if it were to be implemented. I would imagine that the vast majority of current enthusiasts would get a licence and stay with the hobby they love.
However, I do feel that the future of our sport / hobby would suffer if licensing came about. One of the attractions at the moment for newcomers is the ease of accessibility. Licensing would create a barrier for many that they might not wish to negotiate.
Existing laws and rules are tough enough. Harsher rules would just adversely affect the law-abiding whilst the scrotes and criminal element will always obtain whatever they want with no regard to any laws.