That is not always true though. If we look at DRAM. There is a reason why we are still stuck with 8GB DRAM as entry level while 99.99999% of tech community including HN has been stating DRAM is cheap and it is only going to be cheaper for more than a decade. The cost to produce DRAM has only dropped 10-20% over the past decade, while pricing fluctuate a lot as with any commodity. Microsoft knew this way back in 2006 ( or even earlier ) when they were designing Xbox.
>What manufacturing changes do you imagine would make that possible?
AFAIK, Not any time soon. You could probably read up on all the issues on thememoryguy [1] or SemiEngineering [2]. But even PLC wouldn't bring that much cost savings, if there are any. There is nothing on the roadmap for the next 5 years. Not even in R&D Labs which suggest it may not even happen in 2030. That is why I am hopping for some news, some progress like [3].
[1] https://thememoryguy.com/how-3d-nand-makes-qlc-and-plc-feasi...