No one knows how it will all shake out. I'm personally skeptical scaling laws will hold beyond GPT4 sized models. GPT4 is likely severely undertrained given how much data facebook is using to train their 8B parameter models. Unless OpenAI has a dramatic new algorithmic discovery or a vast trove of previously unused data, I think GPT5 and beyond will be modest improvements.

Alternatively synthetic data might drive the next generation of models, but that's largely untested at this point.