I’m not sure what your point is. Yes, Apple has a license to the architecture. Since Apple paid for the creation of Arm, I assume it’s actually a perpetual license and they aren’t paying anything anymore, but who knows.
But if Arm goes away, then Apple can easily extend the architecture itself. After all, they certainly already work with Arm to get features that they want added to the ISA. And good chip designers can create their own architecture - they don’t need Arm to do it. At AMD, we created AMD64 (now x86-64) - I actually helped design part of the ISA. I didn‘t have to go to some “architecture experts” at some neutral company to do it. Intel also creates its own architectures and architectural extensions.
So, once again, assume Arm goes away. Goes out of business. Stays in Business but stops providing new architectures and extensions. Gets bought by nVidia who keeps all the good extensions for itself. Whatever. In those scenarios, Apple would be MUCH better off extending Arm as it sees fit (and probably making its extensions available by license to others to use if they want), instead of switching to RISC-V (which is currently a horrible mess, due to its immaturity, a few weird technical decisions, and the fact that you never know what extensions will exist in what RISC-V chips).