I still see this more like there will be "devs" that only know how to use LLMs and not any layer under it.

Just like there were web devs that only knew jQuery but not any actual JS. Game devs that know only Unreal Engine or Unity but nothing about DirectX, OpenGL, or Vulkan. C/C++ devs that know nothing about LLVM IR or the actual bits their compiler generates. It can also be a poor understanding of the layers in the abstractions above you too.

I find a lot of value in being able to understand levels beneath the layer I'm mostly working in. There are things, even/especially with LLMs, that I can grasp because of my deeper understanding.

But there have been plenty in our field that have only known their level of the abstraction for quite a long time. Every time there is something introduced that lowers the barrier to entry to making things, there is a version of this "but they don't know how it really works..."