> Rather than cost to consumers going down over time, it will likely go up. Not because it can't get cheaper/more efficient - but because it increases companies' profit.

As shown in the OpenRouter links you provided, there are over 30 distinct providers of these open-weights models, the majority of them supporting ZDR. They can't raise prices because it's a near-perfect marketplace and if they do, someone will just lower them to compete as long as marginal revenue >= marginal cost. There's no moat or other economic factors (e.g. collusion; hard to do with 30 actors) to allow for price control.