Maybe this will stimulate some sort of response.
Consider me stimulated.
I taking a chance here. I'm not specifically approved for this topic. But since you are looking for comments, I will provide some.
Let me first state that I have some disagreements of my own with neo-Darwinism - see
Criticizing neo-Darwinism. Like you, I agree that evolution has happened in the past. Unlike you, I expect evolution to continue.
The main point of your thesis seems to be captured by the word "prescribed". Unlike you, I am not a determinist. But I won't argue that point. It seems to me that there is no possibility of empirical evidence that could distinguish between determinism and indeterminism. Roughly speaking, determinism says that if we could rewind the tape, and play the history of the universe a second time, it would turn out the same. Indeterminism says that it would probably turn out differently. We don't have the choice of rewinding the tape, so there is no certain way to distinguish between these two theses.
You keep asking people to address the substance of PEH. I am having trouble finding what that substance is. Compare with neo-Darwinism. Even though I have my disagreements with neo-Darwinism, it does provide a useful heuristic for making predictions. I am unable to find anything comparable in your thesis. By saying that evolution is prescribed, you are denying any possibility of prediction unless the prescription is known. And you don't seem to have provided any insight into how we could find out what is prescribed for the future.
If you are able to better explain the substance of PEH, in the form of what kind of testable empirical predictions it can make, that would be much appreciated.