I expect parts will last quite a while, and parts will not. I was given a photograph for christmas because what I asked for was backordered. It finally showed up as available on Brownell's website. I ordered it that day. They processed my order and told me it was out of stock. So either it never was, or sold out before they got to my order. I lean towards the former, given estimates from other companies. Most of them don't think they'll get a tumbler in stock for 3 months or more.
Nobody is going to pay to ramp up production for this demand level because nobody is even hinting that this demand level will remain. Even the question we're answering assumes the premise that demand will fall again. Would YOU pay to ramp up production for temporary demand? Sure they may pay some overtime, but not for production facilities and equipment...
I think it'll be longer than a few months, and it'll take longer to get supply back than the demand will be there as companies trickle back into "in stock" statuses.