GPT3 and other deep models cannot predict the future. They can only generate alternative presents.
The only reason would be hitting the hardcoded input length limit.
The novelty does no go beyond the variability of the training data.
And so deep learning cannot generate futures that are both surprising and general.
In the context of conversations, no doubt that it can generate realistic answers. They will just be regurgitations of the training data. They might seem novel to you because you haven’t experienced all the discussions of the training set. But they won’t be novel to humankind and won’t project it into an actual future.