Assuming that LLMs hamper gaining true experience and mastery of a language, and further assuming that LLMs will play a significant part in development (especially for juniors)… it seems to me that new programming languages and frameworks will have a significantly greater hurdle to overcome going forward, compared to what they faced in the past.
I think that LLM’s ability to understand any language, programming or otherwise, is almost entirely a factor of how much training data it can get its claws on. In the cases of new programming languages, it probably won’t be able to do much of anything.