The point that the article makes is about opening up NeXT to other hardware platforms. So while from one perspective, you might argue it lives on inside Apple, you could also argue that's where nextstep died.

In the early 2000s I worked for a company that went all in on NeXTSTEP a decade earlier. The product was developed in a "4 GL" called 4D or 4th dimension.

We had to do a painful migration to windows nt/xp because NeXTSTEP was discontinued and apple actively fought to kill attempts to fork or open source the code base.

NeXTSTEP drivers were written in Objective-C, originally OS X used C++ subset based on COM (IO Kit), now moved into userspace and called Driver Kit, in homage to the NeXTSTEP DriverKit name.

NeXTSTEP was focused on OpenGL and Renderman, OS X used OpenGL, macOS is now using Metal.

NeXTSTEP drivers were on kernel space, now everything is moving into userspace.

NeXTSTEP used Display Postscript, OS X moved into PDF subset, nowadays that is only part of the rendering stack.

NeXTSTEP had a X Windows Server as well, on macOS that is now gone.

macOS Finder is nothing like the NeXTSTEP file application.

NeXTSTEP supported a concept similar to OLE, it is nowhere to be seen on macOS.

Let's hope projects like https://github.com/trunkmaster/nextspace succeed.