You know what this reminds me of?
Fountain pens.
Let me ‘splain…
Nestled within my guitar enthusiasm is an interest in fountain pens. I’ve used them for about thirty years. Well, there is a certain refillable fountain pen mechanism on some vintage fountain pens which uses a lever on the outside of the pen to compress a rubber sac inside the pen. If the nib of the pen is dipped into a bottle of ink and the sac is compressed, when the lever is released, ink will be drawn into the sac as the sac expands.
What does this have to do with tubes?
Well, for many years it was very difficult for pen enthusiasts to source replacement sacs. Those who had lever-fill pens usually just had them for collectibles, but didn’t actually use them. However, many years ago, seeing the market within a niche community, certain entrepreneurial types began making sacs for vintage fountain pens.
The point?
The guitar playing, tube amp using community is WAY bigger than the fountain pen community. Guitar players represent a significant, recurring market and source of income. A factory in China ceasing production is not going to end the supply of valves for the world. Someone with sufficient resources will see the dollar signs and the market potential and make tubes. Sure, they may be harder to get, and they may be pricey, but I have very little fear that they are completely going away.