Are you aware, what hardware is currently needed to run GPT4?
Something bigger than a smartphone usually.
So small mobile optimized LLMs will come, or are rather already there - but if they would manage to make the big GPT4 modell run on an iPhone, that would be a pretty big thing in itself, way larger than GPT5.
But llms are relatively rarely used, and on the other hand, perf/latency is important to ux, and perf is variable(simple question, complex question, visual work).
It really wont be that long until we see some ~GPT4 llm embedded locally in a chip on the next iPhone release...