What a great article from LWN. It was well-worth reading. As someone who was excited about the NoGIL from Sam Gross when it was first posted here, I think I'm beginning to change my mind after reading this article and reflecting on my own personal experiences.
My experience is with writing backend systems in several different languages (including Python) at various volume/latency/throughput levels. I've basically worked on only two types of systems -
1. one that exposes some sort of an endpoint to the network - it accepts requests of some kind, does computation and other network requests and sends response of some kind (including long polling, ws etc).
2. reads a message from a "queue" (could be database, could be based on polling another api etc) and does computation/network calls and basically sends it to other queues.
Nothing else. Huge variance in specific requirements, but that's it. For the first type of system, latency matters more. For the second system, throughput matters more.
For the first type of system, I want to be able to spin up threads in response to requests, without worrying that an endpoint is too computationally heavy and might block others. I want to be able to share connections to databases in a shared pool. NoGIL would be useful here.
For the second type of system, I can't remember the last time where I wrote one where I had in-process parallelism/concurrency with shared resources (even in langs where there's no GIL). It would just get too confusing and hard to reason about. Any optimizations were mostly based on intelligent batching. For parallelism, you'd just have multiple _completely_ independent processes, probably across multiple machines.
I would absolutely be disappointed if NoGIL meant compromising on the quality of of the second type of system here. In practice, most of my mental bandwidth today goes towards making the second type of system better.