The core of your argument is that using LLMs is a skill that takes a significant amount of time to master. I'm not going to argue against that (although I have some doubts) because I think it's ultimately irrelevant. The question isn't "is prompting a skill that you'll need to be an effective software developer in the future" but "what other skills will you need to do so", and regardless of the answer you don't need to start adopting LLMs right away.
Maybe AI gets good enough at writing code that it's users' knowledge of computer science and software development becomes irrelevant. In that case, approximately everyone on this site is just screwed. We're all in the business of selling that specialized knowledge, and if it's no longer required then companies aren't going to pay us to operate the AI, they're going to pay PMs, middle managers, executives, etc. But even that won't be particularly workable long term, because all their customers will realize they no longer need to pay the companies for software either. In this world, the price of software goes to zero (and hosting likely gets significantly more commoditized than it is now). Any time you put into learning to use LLMs for software development doesn't help you keep making money selling software, and actually stops you from picking up a new career.
If, on the other hand, CS and software engineering knowledge is still needed, companies will have to keep/restart hiring or training new developers. In terms of experience using AI, it is impossible for anyone to have less experience than these new developers. We will, however, have much more experience and knowledge of the aforementioned non-LLM skills that we're assuming (in this scenario) are still necessary for the job. In this scenario you might be better off if you'd started learning to prompt a bit earlier, but you'll still be fine if you didn't.
Maybe AI gets good enough at writing code that it's users' knowledge of computer science and software development becomes irrelevant. In that case, approximately everyone on this site is just screwed. We're all in the business of selling that specialized knowledge, and if it's no longer required then companies aren't going to pay us to operate the AI, they're going to pay PMs, middle managers, executives, etc. But even that won't be particularly workable long term, because all their customers will realize they no longer need to pay the companies for software either. In this world, the price of software goes to zero (and hosting likely gets significantly more commoditized than it is now). Any time you put into learning to use LLMs for software development doesn't help you keep making money selling software, and actually stops you from picking up a new career.
If, on the other hand, CS and software engineering knowledge is still needed, companies will have to keep/restart hiring or training new developers. In terms of experience using AI, it is impossible for anyone to have less experience than these new developers. We will, however, have much more experience and knowledge of the aforementioned non-LLM skills that we're assuming (in this scenario) are still necessary for the job. In this scenario you might be better off if you'd started learning to prompt a bit earlier, but you'll still be fine if you didn't.