Yes, there are many costs connected with stockpiling that I didn't go into: my comments was all about supplying the market. As you say, it ties up company money and, if they have to hire additional warehouses, has direct costs as well.

My best guess is that Just-in-Time systems will have to change to 'small stockpile' systems. Whatever system you use, you need the 'demand' to equal the 'supply'.   So conceptually you always have a supply, a buffer area to smooth out variation and a demand that takes things out of the buffer. Just-in-Time is about making the buffer as close to zero as possible. I suspect that for the foreseeable future we will have to have lots of 'non-empty' buffers to smooth out delivery issues. Which, as you say ties up company money and may incur additional warehousing costs.