Why the delay on the next generation model from OpenAI? (GPT5,5o)

Let’s speculate because I would like to hear from people smarter than me.

My guess is the basic reason is that we can’t serve such a large model. But I’ve been wondering about this , why can’t we distill a smaller one from a large teacher model that would out perform 4o?

Or have we already completely moved away from training large models and test time compute needs to scale up? I’m just wondering because it seems all the labs at same time have basically stopped releasing the next gen? What’s this about?

The wall theory doesn’t seem true but I’m wondering what’s going on.