What i've heard is that no one creatively is impressed with the Ratatouille ride, so the "same" thing coming to Epcot is unlikely. A ride of some sort based on it? Maybe, but likely not that particular one.
Japan's main sponsor is Mitsukoshi. Mitsukoshi likes money. Mitsukoshi sells lots of Ghibli stuff. Mitsukoshi would have to surrender a large portion of their complex/floorspace to allow the addition of an attraction at this point. So, it's possible but it's not terrible plausible.
Big Hero 6? No, floppity flop flop.
- - - Updated - - -
To note, France is the only place to serve breakfast in World showcase (well, open without a reservation) and one of very few places to even offer breakfast at Epcot.
Frozen-strom would need to open with the park, it just has to. Frozen plus low capacity plus tiny space does not equal opening at 11am. Unless you want a second rope drop comprised of angry people with strollers trampling the whole of the Mexico pavilion. If it's open with the park and drawing crowds, they need food. The Kafe in Norway is not capable of handling this. They need more food options.
Plus, more people in World Showcase who are not adults drinking (that is seriously like 85% of the population on a regular night). They've got to do something to accomodate Frozen coming to norway outside of Norway itself to make the park work.