[bradpdx]

This isn't a matter of taste, tone or engineering - it's economics. Tubes will be around to service their current niche until that becomes impossible to profitably sustain.

There are several variables, including the size of the guitar-playing market and supplies of materials used in manufacture. I suspect that tube prices will gradually inflate as the technology becomes increasingly isolated from the mainstream and it is thus more expensive to procure raw parts, materials, tools and expertise. When a replacement set of tubes reaches a certain cost point, players will adjust just as in any economic system. The music won't stop, that's for certain.

I love my tube guitar amps, but I don't expect audio tubes to be available indefinitely. Perhaps long enough for my lifetime, but beyond that is hard to say.