I should have expanded on my first post more. It sounds like I’m saying it would fail because of Rowling, but she was just an additional reason. The other reasons would be that if this does become a hit, ten years is a long time to lock in for TV, especially in the streaming age. Unless you lock the actors in early for a contract, that’s going to be an insanely expensive show by the end. This coming from HBO Max which has not only been deleting stuff from its library to cut costs, but has also literally filmed a whole season of a show and then just didn’t release it to save costs.
On top of that it’ll be hard to come close to the chemistry of the original cast. They nailed every character the first time around. If they manage to bat 1.000 and create another worldwide phenomenon from the same content again, good for them, but it wasn’t just the content from the books that made the movies so popular.