There's still 9 months left until release, that's plenty of time for optimization and polishing.
With a game this massive and complex, I suspect the final game will still have some dips when physics/alpha effects/open areas coincide, but most games tend to run smoother on release than they do in demos 9 months out.
I just hope they don't throw in the towel and decide it's easier to make it NX only than to get the Wii U version running smoothly.