But to your point, that is exactly how American companies like to play now. No one is stopping them from screwing over the consumer.
I have a Micron near me and they are building another chip facility but we are years away still so I suspect China will beat them to the punch.
The difficult question is more whether foreseeable memory demand will remain at the current level, grow even further, or shrink again.
The up-front investment of a memory fab is measured in billions, and takes years to construct and get running. The margin on the chips themselves is terrible, so without scale its not worth even trying. DDR5 is a industry standard that takes some effort to conform to, but the licence fees is a drop in the bucket to the cost of creating a fab.
The fabricators were cautious about increasing production, and slow to start planning. It takes further time to build up capacity, and if the demand drops down, they may end up producing dram at a loss when the market flips over to oversupply. The demand whiplash could kill any company that dared betting on increasing production. See the "bullwhip effect" https://en.wikipedia.org/wiki/Bullwhip_effect which has killed semiconductor fabricators before.
There is a discussion to be had about how to maintain national semiconductor production in Europe and US as a strategic industry, but historic attempts have all failed.
If it was just variable costs and new capacity was available today they’d do it. But there are substantial fixed costs and delays to increasing capacity, and that uncertainty makes it risky.
Really?
How long do we have to wait until that ... cost reduction hits us?
Safe to say at least a year or two. It'd be shocking if it took a decade.
Likewise it's probably dwarfed by improvements in how we make dram - continuing the roughly exponential (maybe a bit less recently) scaling of chips - but not necessarily.
The 2x from returning to previous costs is interesting because it's practically guaranteed, and it's on top of everything else. We're just currently "overpaying" (relative to the stable market price) for the manufacture of dram because of a sudden increase in demand.