Nothing really surprising here. It's about what I expected for an open world game of this scale. I was only hoping against hope that it would at least have some AA, keeping everything else the same, but I figure that would be too much.
As for any performance improvements from now until release? I dunno if that's gonna happen. I can't recall any playable demo Nintendo has ever shown in the past that had improved performance by release. I figure Nintendo may feel that the frame rate drops are rare and not that significant so as to not warrant any additional effort to optimize.
The bigger question is what is Nintendo going to do with the NX verssion? Nintendo can't make that version that much superior looking since they also want to sell copies of the Wii-U version. I'd figure at most we'll probably get a resolution improvement to 1080p and that's it.
1. I am pretty sure Skyward Sword did.
2. The demo build could be months old, and its Nintendo. They are not known for shying away from putting in the effort to optimize their games.
3. Pretty much the fate of the Company Depends on the sucess of the NX, and Zelda will be their number one card to get core gamers to buy it.