My bet: GPT-5 leans into parallel reasoning via a model consortium, maybe mixing in OSS variants. Spin up multiple reasoning paths in parallel, then have an arbiter synthesize or adjudicate. The new Harmony prompt format feels like infrastructural prep: distinct channels for roles, diversity, and controlled aggregation.
I’ve been experimenting with this in llm-consortium: assign roles to each member (planner, critic, verifier, toolsmith, etc.) and run them in parallel. The hard part is eval cost :(
Combining models smooths out the jagged frontier. Different architectures and prompts fail in different ways; you get less correlated error than a single model can give you. It also makes structured iteration natural: respond → arbitrate → refine. A lot of problems are “NP-ish”: verification is cheaper than generation, so parallel sampling plus a strong judge is a good trade.