Would you watch a completely animated show?
Would you watch Harry Potter as an animated show? If it adapted the books closely? Would it be able to start a time in which we get more adult animation in consideration for adapting a book? This might just be wishful thinking, but bear with me. I hope I can explain this with clarity.
I think that, if a Harry Potter animated series would do well, it would open doors for animation for adults to be more common as a choice for adapting books (or other mediums). As Harry Potter appeals to all ages, not only children.
Harry Potter is one of the biggest IP's, I believe next to Star Wars and Marvel. I am not in any of those two fandoms, so I can't speak for how well received their animated shows are, but I do know they have animated shows next to their live-action ones. Not sure how fair such a comparison is, as I believe their target audience is different. The only comparison of an animated show geared at adults I have is the Castlevania animated show, of which I've seen one season and it was a long time ago.