It's more about what the writers do in accordance with the whims of their fans than anything else now. Pyrrha being resurrected, while a growing want among the fans now, is still far from being the majority. Thus, it will not happen. And at this point, I, who saw several narrative reasons to do such a thing after season 3, now have seen them retcon so much to either kowtow to the fans or accommodate whatever short-sighted thing they cooked up, that I MUST question if such a revival was part of "THE PLAN".