I'd agree... were it not for the odd way they've been handling the promotion for the movie this year.
Generally speaking, the movies have their full titles revealed in January or February, after the Mythical Pokémon starring in the movie has been revealed. This year, as was the case last year, the movie's just being promoted with a generic placeholder "Pokémon XY&Z The Movie 2016!" title, without the full title having been revealed yet.
However, this year it's slightly different. Volcanion, the last Mythical of the generation and the apparent star of the movie, has already been revealed- indeed, he was shown off for the first time when the movie was announced back in December. However, we still don't have even a partial title for the movie- if Volcanion was indeed the main reveal for the movie, then you'd have thought the title could have been revealed at the same time it was. Last year, for example, "Pokémon XY The Movie 2015" became "The Archdjinn of Rings- Hoopa!" as soon as Hoopa was officially revealed. We have our Mythical- why don't we have the title?
There is precedent for this- back when Gen V was drawing to a close, they revealed Genesect notably early and had it present and correct at the first reveal of the movie. This served to obfuscate the big new reveal for the movie- Mega Mewtwo Y, which served as both a return for one of the icons of Pokémon, and the first ever introduction of the concept of Mega Evolution to the franchise. They haven't really treated any big Mega Evolutions in the same way since- Mega Latias, Mega Latios and Mega Diancie were given muted, tossed-off reveals, rather than being deliberately kept a mystery and hyped up as a world-changing new reveal a month in advance.
The way I see it, the big reveal's pretty bloody likely to be one of two things, given the level of hyperbole- a whole new concept for the franchise on the level of Mega Evolution (the language being used here is pretty similar to the language that the magazine was using when promoting the reveal of the Mega Evolution concept), or the start of a new generation of Pokémon, whether a game featuring them is forthcoming or not. Given all this, and the whole mystery around the title of the movie... I'm slightly leaning towards it being a new Pokémon reveal. It's not a certainty, but it all fits quite nicely.
Of course, Coro Coro could just be blowing smoke over the importance of its reveal, but I'd be a little surprised. They tend to be quite good at avoiding overhype.
Eh. I'm not getting myself overhyped or anything- just drawing conclusions from the evidence in front of me. If it's wrong, so be it.