> Maybe once LLM improvements asymptote further?

Maybe! But it also doesn't require the rate of improvement to slow down. As long as some current model is eventually "good enough" for general use, it could still be a market-killer at a very low marginal price thanks to ASIC. Even if slower, much more expensive models are 10x better, that doesn't actually diminish the utility of the ASIC model, as long as it's "good enough".