Oh woah, this is pretty awesome. I've always been curious about how everything connected.
I assume that perhaps the large white clouds are going to be future places? For example Strangeville might be were the current icon for San Myshuno is, perhaps it's own island. Similarly, perhaps the tropical island lays behind the Windenburg icon cloud.
Thinking this way, it gives me hope that there are multiple more new worlds coming to us before the end of TS4. Assuming this is official artwork, of course.
I did however, have a small moment of confusion. I use replacement maps for my worlds, as I prefer the art style and the slightly more detailed approach, so I was slightly confused in regards to what i was actually looking at, haha.
EDIT: for anyone interested, the replacement maps can be found
here