Lets forget about WW3, but even the risk of a TSMC monopoly (or rather a TSMC+Apple monopoly) and price gouging is existential enough that Amazon has plenty of risk sitting on the sidelines regarding fabrication.
It would be very inline with AWS to start fabrication as a service to avoid this existential risk. They can always start with easier node sizes for SSDs / DDRs / networking / automotive chips / etc. Even if only to self-source, Amazon alone needs a roughly-infinite supply of these speciality chips. Even totally new innovation that "only Amazon-types" need, like a Silicon interconnect the size of a Datacenter Cabinet (if the yield is reasonable) would be interesting to see.
They could even make a play at SiC chips[0]. If they can make it cheap and at small enough node sizes, I'd love to see what innovation SiC could bring to datacenter design. eg more efficient power supplies of each server/rack/cabinet.
[0] https://www.investors.com/news/technology/silicon-carbide-ch...