I'm really curious about the number of changes/overhauls the worlds will require, as many lots don't line up with the street, and there are often sidewalks and such in front of them. Plus, it seems that, quite often, the scaling of roads/highways isn't consistent. Thus, I'm sure that if (hopefully) they do it, it's going to require massive retooling of several of the worlds.
I do hope that they will either be a game update or most likely both, the big summer EP.
Maybe this could explain why it took so long?