This assumes AI model improvements will be predictable, which they won’t.

There are several simultaneous moving targets: the different models available at any point in time, the model complexity/ capability, the model price per token, the number of tokens used by the model for that query, the context size capabilities and prices, and even the evolution of the codebase. You can’t calculate comparative ROIs of model A today or model B next year unless these are far more predictable than they currently are.