> I wonder how much of the '5 release was about cutting costs vs making it outwardly better. I'm speculating that one reason they'd deprecate older models is because 5 materially cheaper to run?

I mean, assuming the API pricing has some relation to OpenAI cost to provide (which is somewhat speculative, sure), that seems pretty well supported as a truth, if not necessarily the reason for the model being introduced: the models discontinued (“deprecated” implies entering a notice period for future discontinuation) from the ChatGPT interface are priced significantly higher than GPT-5 on the API.

> For companies that extensively test the apps they're building (which should be everyone) swapping out a model is a lot of work.

Who is building apps relying on the ChatGPT frontend as a model provider? Apps would normally depend on the OpenAI API, where the models are still available, but GPT-5 is added and cheaper.