Median response is pretty specific. It would take a lot of justification to arrive here. The base model is predicting the next token. Even saying it has personas is anthropomorphizing this process.
And while GPT4 does not have a "world model", can we please move on from the stochastic parrot argument?
My inability to emit more than one word at a time (either spoken or written) does not mean I lack multidimensional planning and conceptualization; why does this line of thinking not extend to LLMs?
The thing is, the phrase "Odds are ... median response across all possible chat personas" is nonsensical in so many ways. How are you going to define chat personas? Once you do this, how do you order them to take a median? Then, why is this something that will happen with some probability? This is not a quantifiable or testable thing that can happen. It doesn't have a semantic meaning. Maybe it has an emotional meaning like "I'm excited about GPT-4", and I would agree about that! :D