There was actually another dev post about this on the Japanese side a week ago to clarify this (here). In every ward, they will add a new area that's completely separate from the current area. So I guess you could kind of think of it like each ward will now have "Zone A" and "Zone B" (where A is what we have now, and B is the new area). They point out in the post that this means that people's existing locations/scenary/services/etc. won't be affected in any way.