Just adapt circuitry to use tubes outside the classic 12A**, 6S**, ECC**, KT**, EL**, 5R**, 2A3, 45, 300B & Russky milieu and there is still plenty of NOS out there to keep going for decades. Lotsa great TV tubes (including cheap damper diodes) just waiting to be discovered. Only takes a little imagination.
it’s far from the end of the world and might actually spark a little innovation..