I think there's room for more nuance here. It could also be a situation of diminishing returns but not a sharp plateau. That could favour the big players. I think I find that scenario most likely.
Search engine tech isn't that much of a secret nowadays? Still it's prohibitively expensive for almost everyone to build a competitive search engine. What if really good AI turns out to be more like that (both training and inference)
For AI, I think that ship has sailed already. OpenAI is the closest to dominance, but not currently the best at all tasks (claude and gemini for some tasks), and everyone else is nipping at their heels, followed by open / cheap models anywhere from 6 months to 1 year behind. Maybe I'm wrong, but as far as I can tell, all evidence points to it becoming a commodity (or utility), similar to cloud computing.
For example AWS is pretty dominant in the cloud computing space, but the differences aren't really that big of a deal for most people and there are services that will extract the cloud for you as a generic services layer. Like OpenRouter does for AI models. Is AWS really better than other cloud providers? Maybe, in some situations, with some requirements, but it's definitely not the general rule. Their focus since the beginning has been layering value on top of this base cloud offering (I'd argue to the point where there are so many services it's confusing AF), and I think it's the same with AI providers. It's even the same players for a lot of it (Google Cloud, AWS, Azure all offer AI services).
At the same time, an AI that stays up to date with world events and everything new that happens, would in a way have to be both a compute platform + a search engine combined? (To find and train on "everything new".)
But most wouldn't need such an AI (RAG is usually good enough, right), for example not needed software development.
Maybe for a limited time a hardware company could get a monopoly? Eg Nvidia. But they sell to everyone, don't they, fortunately (except for export restrictions)
It's all been priced in though.
If the gains plateau, then there's really no need to make productivity sacrifices here for the societal good, because there's so much competition, and various levels of open models that aren't far behind, that there will be no reason to stick with a hostile and expensive service unless it's tooling stays leaps ahead of the competition.
If the gains don't plateau, well then we're obsolete anyways, and will need to pivot to... something?
So I sympathize, but pragmatically I don't think there's much point in stressing it. I also suspect the plateau is coming and that the stock of these big players is massively overvalued.