Can be possible. In the past the last movies of the anime arcs mostly introduce a new Pokemon, but this is not true because Lucario and the Mystery of Mew was the second last movie, but Manaphy was introduced in the last movie of Hoenn. Zoroark was revealed in the last movie of Sinnoh, and Mega Mewtwo which is not really a new Pokemon, in Unova. LAST BUT NOT LEAST Latios and Latias were revealed in a Johto Movie, I think it was Pokemon Heroes.
Magiana (Magearna in English), can possibly be linked to a new region, since the official Pokemon site describes it as a "New mythical Pokemon", so this means it is possibly a new gen Pokemon because Magearna doesn't exist in the data for XY/ORAS. Magearna's name is also included in the movie title, so were the names of Zoroark and Lucario.
Or if I'm wrong, and as Doctor Disco said, it might be referring to a NEW Legendary in a new Kalos game.