For SotA models future costs are an uncertainty to take into account. But for weights-available models like deepseek or qwen there are plenty of providers that just own GPUs and run inference, batched over many customers. Those have very little incentive to run inference as a loss leader. What it costs today is very likely the true price, with some marginal profit for them

The only thing you really have to worry about in that case is them cross-financing by siphoning off your data and selling it, or them being run by an intelligence agency, or something like that. Of course they all promise that that's not the case, and some have all the certifications you can wish for