I thought about this as well. However, even though this is occurring the way it is, there is no evidence for this other than the DLC. Here are a couple of things I would think about to help with speculation: 1) The release dates of the two previous Animal Crossings so we know the "development gap," I like to call it and compare that to the development gap so far. 2) Nintendo is full of surprises, so one can never fully predict the path this company goes in unless a leak takes place.
Evidence that is brought up from the DLC is the characters/courses themselves (Isabelle, Villager, and all courses in the upcoming AC cup). BUT it's more than just that! Link will be DLC also (at an earlier time)! Why is this important? It's important because there is a Legend of Zelda game coming for Wii U TBA 2015. These two things could correlate with each other. Either that, or it's just sheer coincidence.
I wish that this all was the case, but Animal Crossing: New Leaf came out just last year on June 9, 2013. The developers probably need more time with AC Wii U tbh, but that doesn't mean that they couldn't announce it though.
