Personally, I hope that Diancie ends up being an event that opens up a new area to explore (bored and just breeding since post game sucks ya know), similar to the Shaymin/Darkrai/Victini areas but much larger obviously. Make it like the Nature Reserve, except put Pokemon in there with HAs that we dont have yet(SF Totodile ^_^), and give it a route or two of its own similar to the isles in FRLG.