GPT-5 is almost certainly already done. But considering they sat on 4 for 8 months with Altman as head, who knows if it'll see the light of day.
They just started development in the last week or so: https://decrypt.co/206044/gpt-5-openai-development-roadmap-g...
There's some vagueness here sure but if they can demonstrate something to that effect, fair play to them i guess.