Computer hardware does not last forever. The harder a piece of hardware has been used, the closer it is to dying. For example, GPUs that have been used 24/7 for several months at full capacity are likely close to the point where they will no longer function, even if they appear to work fine now.
If you don't believe that is true, then you must be under the impression that computer hardware lasts forever. If that is the case, I don't know what to say to you.
As for what companies will do, why would they choose the path with the most risk? Right now AMD, Nvidia, and the various board partners have two real choices in regards to the matter.
1.) Keep production and costs about the same and run the risk of a shortage.
2.) Increase production and financial investment to create more GPUs, which runs the risk of having far too many GPUs in stock.
If they choose option 2, and become over stocked on GPUs, they then need to either sell them at a lower price that may constitute a loss or decreased profit margin, or they will need to pay to store the GPUs until they can be sold off at regular prices. Either option increases costs for the companies while reducing overall profit margins.
Option 1, however, doesn't see an increase in spending to produce GPUs, doesn't run the risk of selling products at lower prices and reduced profit margins, and doesn't force the companies to pay to store excessive amounts of products. Plus, the shortage is likely good for all of the companies involved, as they are able to sell all of their products with virtually nothing left on the shelf, and they are selling at higher prices.
If you were a company, which would you do? Obviously the one that offers the greatest financial return for the least investment.