That's even more inevitable than operating systems becoming commodities.

Think how easy it is to switch from one AI to another.

There is no vendor lock, because vendor lock requires dependence. Dependence requires dependencies that are hard to replace, and those are necessarily built on predictable, deterministic behavior (the quantity and variety of which has to be prolific so that replacing it is a monstrous effort). The quantity and variety in the LLM is certainly prolific, but without the determinism, it's replaceable, because the competition does not have to nail down any specific details. It just needs to come up with something similar.

Higher level workflows based on AI can be retargeted to different vendors, so the different AIs are not even like operating systems, but more like device drivers. The way organizations are integrating AI is already positioning it as a commodity.