Forgive me for my ignorance, but isn't it possible to patch 3DS games without too much trouble? I don't know if you can fully add things like Pokémon or Abilities, but Nintendo has already sent out patches for the games to correct glitches. Would adding another Pokémon or form via DLC be too hard?
In short, yes. Besides, if they could do that, why leave in Hoopa, Diancie and Volcanion?
Continuing on my previous post, I just had a "loud thinking" session on IRC, with helpful input from many other users.
Considering that the games have shown to be picky about what new content they can be compatible with whenever newer versions are released, it seems strange that GameFreak would only leave two Mega Stones hidden in the coding in X/Y. Mega Lati@s are the only X/Y compatible Mega Evolutions that GameFreak haven't acknowledged yet. Is it possible that these two are the only new MEvos we will see in ORAS? If GameFreak planned on adding more Mega Evolutions this generation, why would they only implement two in X/Y? If they planned on making more Mega Evolutions for X/Y available through patches and events, why did they leave Mega Lati@s hidden in the game files? They'd have a much, much better chance of keeping them secret if they just kept them as patches alongside all those alleged extra MEvos. No, indeed, as far as X/Y is concerned, it seems like Mega Lati@s are the
only new Mega Evolutions we're going to get.
Does this mean they will be the only new Mega Evolutions we will see in ORAS?
Not necessarily. While Mega Lati@s may be the only two new MEvos transferable to XY, there may still be plenty more in store for ORAS. Formes and such have been commonplace since FRLG was released, without causing any trouble to the "pioneer games" of the generation. Tweaking existing 'mons is no big problem. In Gen. 6, it's just a matter of playing the Mega Evolution animation, and changing the stats mid-battle. The model would have to remain the same, though (not at all different from how sprites have stayed the same, for, say, Shaymin in D/P). If this works as I think it does, in theory, you could create a hack Mega Evolution for any Pokémon and use it in battle. After all, you can hack in things like Wondertomb already, so this would just be different in that the Pokémon's type and stats change mid-battle instead of before the battle.
Then remains the question: Why, indeed, leave Mega Lati@s in X/Y? What would the point be in leaving data for only two Mega Evolutions, if they're going to add a bunch more later on? Why only make the two transferable to X/Y, while the remaining new Megas have to bang against the walls of incompability?
The answer, I think, is that Mega Lati@s (or at least, the Lati@site) won't be available only through ORAS. I think Latias/Latios, holding their respective Mega Stones, will be distributed as an X/Y event
before ORAS hits the shelves. It will build hype for the new games, give people a taste of Mega Evolutions to come, and it will allow you to get both Latias and Latios in your possession. Heck, they did this with Blaziken already.
TL;DR, I think that:
1) There will be no new Pokémon or Mega Evolutions released
for X/Y that we don't already know of.
2) There will be more Mega Evolutions available in ORAS, but they won't be able to be transferred to X/Y, just like Rotom-A, Giratina-O, Deoxys-A, Tornadus-T and so on were uncompatible with their "parent games" (yet they could still be used in battle against them).
3) The Lati@sites are event items to be released for X/Y before ORAS come out.