That reminded me of how back in 2008 I removed the GIL from Python to run thousands Python modules in 10,000 threads. We were fighting for every clock cycle and byte and it worked. It took 20 years for the GIL to be removed and become available to the public.
Simply removing the GIL and running 10,000 threads seems very unlikely.
What was the use case?
A security scanner, for example, we had to check tens of thousands of IPs of global exchanges for backdoors overnight while the exchanges were offline