Deprecation notice: upcoming model shutdowns in 2026

I wrote a longer post about the broader user-side impact here:Restore 5.1 in ChatGPT: Replacement Is Not Migration - OpenAI Is Breaking Power-User Trust My concern is not only this specific shutdown, but the repeated loss of stable fallback paths for power users — first in the ChatGPT UI, and now potentially in the API as well. For some users, 5.1 is not just an old model. It is a proven assistant behavior that newer models have not fully preserved.