Restore 5.1 in ChatGPT: Replacement Is Not Migration - OpenAI Is Breaking Power-User Trust

A shorter summary of my point: My request is to restore 5.1 in ChatGPT, or at least preserve access through API / paid legacy access. I am not asking OpenAI to stop upgrading models. I am asking OpenAI to preserve the assistant behavior of 5.1 while improving context length, data analysis, tool use, reasoning, and task stability. Newer models may be technically stronger, but many of them feel safer while becoming less like real assistants. They often feel more like customer-service systems: polite, careful, but not truly entering the problem. Replacement is not migration. If a new model is truly better, power users will migrate voluntarily. If users have to be forced into migration by shutting down the old model, that suggests the replacement has not preserved something important. For AI assistants, continuity is not an extra feature. Continuity is the product.