I'm not sure I fully buy this argument. I think programming languages are chosen for projects based on a number of different factors, speed being one of them, but developer productivity being another (and there are certainly many more). Given that there isn't usually going to be one language that is the best choice for every single factor, it seems pretty natural that some teams might pick Python due to productivity being more important but still have some need for better performance, and other teams might not be able to compromise on performance and have to resort to something like Java or Go or C++ but still would be able to iterate faster with something higher level. It's definitely not a given that there are enough potential projects that would get enough benefit from removing the GIL to make it worth it, but it seems silly to claim that anyone would would get any possible benefit from performance would never choose Python for other reasons.
There are enough choices that offer Python's productivity alongside JIT/AOT options, better supported from the community than PyPy.
As for the C, C++, Fortran libraries with Python bindings, any language with FFI can call into them as well.
I would say, Python's adoption while lacking performance is what is now building pressure to avoid specific Python communities to leave Python and migrate into one of those ecosystems in search of a better mix of productivity/performance, without being forced to use two languages.
Ooh, a Clojure .NET implementation? This is news to me. From a quick look at the website, it looks really good... but how is it in practice? One of the major advantages of F Sharp's .NET integration is that it's developed by Microsoft, as of course they pretty much created the ecosystem from scratch.
But it is being continuously kept up to date by Cognitect, along with active development on a clojure-clr-next version. Maybe it has a bigger population of non public users.
Also: here's another implementation of Clojure on CLR, "Morgan And Grand Iron Clojure Compiler": https://github.com/nasser/magic (see also http://nas.sr/magic/) of which there's a great cmpiler implementation talk (at Clojure/North) somewhere on Youtube.
