> And we're heading toward a world where software companies let their users change the product themselves, since with an LLM that's easy. So if a company builds a good opinionated domain language for its product, everything its users build on top of it will be much better, because they start from the company's opinions and not from scratch.

This is a bold assertion, and one I think undermines the merits of the argument.

"Change the product themselves" - I haven't seen any software company or discussion propose doing this. I'm not sure how it'll work. It sounds like it blurs the line between configuration (letting the user toggle certain classes of existing behaviour) and forking (the user now owns the contract with the product).

Perhaps the idea is something like an embedded scripting language as used in some games, where users can write custom snippets to glue together what they want. Or a relational language to generate custom visualizations from raw data. These are the only forerunners of the concept that have found actual market fit to date that I'm aware of.

It's hard to generalize where else this would be useful outside of these domains, and in any domain I can think of - UI interfaces, data analysis, procedural generation - there is already a dominant language runtime bound to the environment (Javascript in browsers, C# in Unity) exposed to customers. Would Common Lisp be able to displace them? If so, why and how would it improve?

Merits on the basis of the runtime itself are meaningful, but the runtime needs to be popular for the value of the PL to be seen.