I'm guessing the true core of this product is still GPT-4, wrapped in whatever new logic they've created to force it through more reasoning iterations.

If o1 was indeed used to create synthetic data to make the upcoming GPT-5, you can perhaps glimpse an interesting level-up process laid out here. GPT-5 could then take over at the heart of a hypothetical o2, yielding a big upgrade. Which would then be leveraged to generate synthetic data to train GPT-6. Which would then form the heart of o3. Etc.