Mega Steelix and Mega Glalie have been revealed, unfortunately in the wake of the excitement there was some reveals that deflated a ton of the hype.
The first reveal was that there would be no trainer customization. Masuda even made the statement that that was a Kalos-thing because it was in the spirit of a "motif of France and really focused on this beauty and fashion aspect, which is why it was a prominent feature in that game
". Personally, I think the trainer dress-up stuff is a whole lot of fluff, albeit fun fluff, but arguing that it's a Kalos-exclusive as if the French are the only people that ever change clothes every day seems like a pretty silly way of saying "we just didn't want to put it in ORAS".
I think the more important reveal was that Pokemon XY will not be receiving a patch to make the new Mega and Primal evolution available
. Unfortunately this seems vague to me, I don't know if it means:
1. It will only strictly allow interactions that don't involve any new features
2. You will be able to interact ORAS with XY, you just can't trade new stuff over to XY
While the latter would be completely reasonable, the former is what most people are expecting and it's made some people pretty salty, because in the past games in the franchise didn't really tend to get outdated until a new generation came along, let alone outdating the first wave of games only a year after they come out.