The existing commercial makers of Tubes tend to be from China and Russia and exist mainly on the Guitar market, often using tooling that was designed for Soviet Military production.
I would guess that the level of technology required to make a Black and White paper, and to make a vacuum tube are on the same order of magnitude. Unlike Film making, there is the posibilty to find the machinery that used to be used to rebuild Picture Tubes for B&W TV sets. The smallest setups would fit in a double garage and conatin the "tricky bits.
As far as Film, I an crossing my fingers taht one of Foma or Ilford can hold on and successfully downsize or diversify to fit the market.