Meloetta... Now there is only one Pokémon left to be revealed (Genesect). If Genesect is in the 2013 movie, they are out of of things to advertise. This would mean that they have to do another movie for a spin-off (like Ranger and the Temple of Sea, but then again it revealed Manaphy), a remake, or they begin teasing generation 6.
Now what else could this Meloetta reveal mean? Keldeo will be distributed at the movie theatres, but you don't think that Meloetta will too, right? ;O I think Meloetta will get the same treatment as Manaphy. You will get it through a spin-off, maybe Pokémon Ranger 4. The mini movie advertises this spin-off. It really makes sense to advertise in the mini movie, too.