GPT-5.6 hitting the performance level of Fable 5 would completely dismantle Anthropic's moat. The core issue right now lies in usage restrictions. While Fable 5 is powerful, it's limited by a 50% quota cap and a 7-day usage cycle. If GPT-5.6 can maintain the same reasoning capabilities while removing these artificial quota shackles, users will have no reason to stay in the Claude camp. The endgame of AI product competition isn’t just about simple benchmark comparisons, but the ultimate battle of the 'performance/usability' ratio. When model capabilities reach a critical point, the one who can deliver seamless, uninterrupted productivity will be the one to retain developers.