As someone who is currently writing their own js framework, llms are able to generate code quite easily. So I am not worried that we will be able to see new frameworks.

Now, about the incentives? Probably less inference costs for llms, which probably means that they are more legible than the current state of the art for humans as well.

Less API changes than let's say react also means that the generated code as less branching although llms can adapt anyway. Cheaper.

Will probably be closer to the platform too (vanillaJS).