I'm a little skeptical of how much is considered irreplacable in the event of a supply chain collapse. I do think that it is possible that we can't make any more bleeding edge tech for 25 years so it means no new phones, quantum computers or large server arrays at today's performance levels. However say some rapture happens, but one not bad enough so we will still be able to scavenge parts and think about computing over our basic survival needs. In that scenario, saying we won't be able to setup even a simple local supplychain to make PCBs for Surface Mount chips doesn't make sense to me. That seems to discredit people's ability to set up basic collaborative processes when shit hits the fan, be it a river powered milling machine, or solar photovoltaics which we are still currently making by the millions so there will be a lot lying around.