This alone isn't evidence of that, but it's not the only data point we have. We've got 20 years of observations. They dropped X11 (and didn't use it for the main display in the first place), created new process APIs (like GCD and background tasks), deprecated standard libraries like OpenGL (and don't support Vulkan), designed their own programming language, etc. All of these point in the same direction.

What will be left? Will it still be "Unix" in any meaningful sense just for having a C compiler and running an old version of Bash? Microsoft Windows did that, too.