Obviously I’m not 100% sure but looking at those Disney sets the centre spine is brick built so is probably that. HOWEVER a hogwarts crest ART set sounds amazing. (Shame about the price tag on it though) edit: hopefully they do drop the price to that as that’s a very good price point.
Just had a look at the Disney princess books and I’d put a strong bet on these new HP ones being like that, which will be a big shame. Hopefully we will get confirmation soon as these could be a great addition.