The vaccum tube analogy is a good one. We looked at a related technology - ribbon microphones - that were also obsolete and came up with acoustic nanofilm to finally make them manufacturable and durable, and sound better, and made a bundle. Ham radio was a big part of the knowledge base that made it possible.
Light sensitive photonic nanomaterials are a hot area today and are in their infancy. Silver based photography is the original photonic nanomaterial. Light sensitive material science is in its earliest stage today.
I visited Ilford two months ago, and TIP too. Both are fine places with excellent people, mostly serving existing markets, and are therefore self-limited. New markets, such as Lomography, expose newcomers and create new product opportunities.
Linear growth/decline curves are passe, and overly simplistic. The world is a much more complex place, fragmented, with no "mainstream" like we had for decades.