Doubtful. Apple can get away with tiny iterations on smartphones because they have the brand and they know people will always buy their latest product. LLMs aren't physical products so there is no cost to switching other than increased API cost, meaning openAI won't be able to recoup the cost of training a new model unless the model is sufficiently different that it justifies people paying significantly more for.

The special thing about GPT-4o is the multimodal capabilities, all the metrics suggest that it is the same size language model roughly as GPT-4. The fact it's available for free also points to it not being the most intelligent model that openAI has atm.

The time to evaluate whether we're starting to level off is when they've trained a model 10x larger than gpt-4 and we don't see significant change.