In this alternative universe, Objective-C would have died, Swift would never happened, and C++ would rule across desktop and mobile OSes (thinking only of Windows, BeOS X, Symbian, Windows CE and what might have been BeOS based iOS).
Also POSIX would be even less relevant, and very few would be buying BeOS X for doing Linux coding.
In my alternate universe, GNUStep or some other implementation of the NS APIs would have allowed Linux/BSD to rise in popularity along with a NeXT-ified Apple. Except that didn’t happen.
I think in your alternate universe it’s likely we’d have seen something entirely different emerge.
GNUStep still looks much like to the on the same state it used to be when I was using WindowMaker in the late 90's.
I regretted the time I once spent on the GNUStep room at FOSDEM, as the only subjects of relevance seemed to be the theme engine, as if there wasn't anything more relevant to get working properly.
What would have been interesting is if Apple had bought Be in 1993 or 1994, and incorporated BeOS tech in System 8, then wound up buying NeXT anyway at the end of 96 and OS X incorporated Be and NeXT tech.
Though it's entirely possible Jobs would have tossed the BeOS tech along with Quickdraw GX, Newton, etc.
Well, the last major revision to the Single Unix Specification was released in 2008. Ever since then, Linux has basically become the defacto POSIX standard. So while glibc may not rule the roost, most POSIX OSes bend to the will of the GNU userland and the Linux monoculture in many ways. It's not really like the old days with Sun, IBM, DEC and even Microsoft with Xenix. POSIX is being washed away a little more every day.
There is a C ABI. The "x86-64 System V ABI" (the ABI for C on everything except Windows on an x86-64, ie a typical PC) was designed by AMD working with early adopters on Linux and other platforms. Here are several extant ABI documents:
The ABI for C needs to agree less stuff than a C++ ABI but it's still quite a lot of stuff, if these things don't get agreed then code won't work unless everybody uses the same (version of the) compiler.
- Chrome OS (where JavaScript and WASM is what matters)
So no, it isn't everything except Windows on x86-64 and then there are all the other OSes running on ARM, MIPS, PowerPC, SPARC, PIC and plenty of other less relevant CPUs .
Also POSIX would be even less relevant, and very few would be buying BeOS X for doing Linux coding.