Maybe this is just my lack of experience thinking, but that seems really unlikely to scale without retraining. The context will balloon with updated syntax for languages and APIs for libraries and so forth. Imagine if, for example, something on the scale of custom elements / web components were introduced in this post-open world. You couldn't fit all the information needed in a local model's context to tell it how to write a new custom element of any real complexity, especially if it needed to interact with the new post-release web transport specification to interact with a new language's client for a new database.