[uranian]

I think the drop in revenue is because the market is really saturated. All those millions of guitars produced are not destroyed, it's not the kind of product that you can apply 'planned obsolescence' to. Instead, the vintage one's are often better sounding and therefore more popular. Also, if you find a good vintage guitar you are almost assured it will remain good as the wood has proven to be stable.

If there is a slow death to guitar than it is because it's almost impossible to earn any money with it, except for the lucky few. Learning an instrument like guitar takes many, many years, which is quite a hobby.. If you would spend the same amount of time in learning software development you are almost assured to have a solid income as result.