Good thing @WDW1974 confirmed Nintendo will be taking over more than just KidZone. My guess is that they'll also be using some land behind Simpsons. Maybe even a little into the MIB plot, who knowsThe Amity Lobster Signage painted on the side of Disaster's Station Building is not so much a tribute as they did not need to replace it but I suppose it kind of works for both. It is there because the park was carefully designed to transition as best they could between lands. San Francisco would turn into Amity quickly with the Wharf theme becoming New England Fishing Town.
If Nintendo does go into KidZone it would really have to almost include Animal Actors and such as the area is not very big land wise to put many attractions even with Barney and Curious George/Fivel combined.
Will answer out of order since you are awake and here!
Nintendo will have a significant presence at UNI-FL. This land will not be simply in the footprint of Kidzone. Larger.
I've already mentioned Beijing. I'd expect you'll see something pop up in Hollywood soon too (that's just an assumption based on something I was told). It goes without saying that Japan will see stuff as a result too.