I don't think they build the ChatGPT subscription interface around workflows. They leave the APIs to cover either custom or pre-built workflows pinned against a specific model. At the same time I wouldn't be surprised if they do end up keeping a couple of the cheaper/smaller older models though, the cost would be low and reduce a lot of the churn friction.

I'm not saying I'd do it that way myself, but it explains why they don't see it as too bold.