> Meta, and big companies with a specialized team might be able to exploit it by making sure their entire stack is GIL-free.
Not really. Most of the popular libraries will have nogil versions ready for sure (numpy, pandas, pytorch, etc). Server applications will probably benefit from being able to serve multiple requests in a real multithreaded environment without many changes (in fact, I bet a lot of HTTP libraries will see simplifications due to not needing to deal with processes for real parallelism). Even packages without changes will probably have at least a small degree of thread safety (for example, two instances of the same object should be independent and could be used in different threads) that allows users to still leverage parallelism.
Not really. Most of the popular libraries will have nogil versions ready for sure (numpy, pandas, pytorch, etc). Server applications will probably benefit from being able to serve multiple requests in a real multithreaded environment without many changes (in fact, I bet a lot of HTTP libraries will see simplifications due to not needing to deal with processes for real parallelism). Even packages without changes will probably have at least a small degree of thread safety (for example, two instances of the same object should be independent and could be used in different threads) that allows users to still leverage parallelism.