It would be no surprise to me if the Shanghai castle is Rapunzel's. Rapunzel's castle very obviously has an overall shape / arrangement of elements very similar to a Magic Kingdom castle, only now with architectural details of an Austrian / Bavarian style. If any of you get a chance to see the images of the castle in the "Art of Tangled" book, the theme park qualities of this castle become all the more apparent.
My Blue Sky hope for Shanghai Disneyland had been for a park with a DisneySea style layout, featuring Rapunzel's castle on its hill in place of Mt Prometheus. But, if the concept artwork from July is any indication, the park will follow a very conventional layout.