There would be no reason to release Eternal Floette, or any other Pokémon, as an event in Pokémon X/Y. Those games are basically dead, and there hasn't been an event in those games since the 20th anniversary, which was 2 years ago. (Source)
However, Eternal Floette has been in the coding in all the games since Pokémon X/Y. Therefore, it is very much possible that they will have an event where you can legitimately obtain this Pokémon sometime in the future. There may even be some sort of Pokémon Z in which they will release it.
So basically, yes. I don't see why it wouldn't be released sometime, considering they bothered to give it its own base stat total and coded it into every Pokémon game.