I don't think it matters if a castle belongs to one princess or serves as a catch-all.
The original Disneyland castle was not inspired by any specific movie. The front facade of the castle is based on the rear facade of Neuschwanstein in Germany. It was going to be called Snow White's castle...but then Walt decided to call it Sleeping Beauty's castle to promote his upcoming film. Hardly princess specific...more a business decision than anything else. But that doesn't make it any less charming to me.
This castle looks fantastic and...while Paris' castle may still be the most beautiful...this one will surely be the grandest...and will also be much more of an actual building than any of the castles thus far.