Considering JJP hit two home runs already with Warner (Hobbit) (WOZ) what would make anyone think they wouldn't have already discussed this with JJP. I'm sure without any doubt that they would want a fully themed game not some assembly line approach for Stern. The owner of the entire HP franchise is a billionaire I'm sure she could care less about making a few bucks off a pinball game. Now is she's seen how the game was approached from Hobbit by JJ she might want to do it simply based on the wow factor.
If you see a HP game I'm sure it will be JJ. I doubt ANYONE would want a HP gamee made by Stern. HP would be another high end collector style game. Look at Star Wars that game is a disaster, who wouldn't have wanted JJ to do that game?
I think everyone. Based on Warners success with JJ I'm sure HP was already discussed. Clearly they want to continue they got Willy Wonka.