Huh, something just came to mind, and I'm more saying this just so if it happens I can refer back to this post and say I "called it". Yes, I know, superficial and petty.
While obviously most things will be calling back to XY, those weren't the only Gen VI games. Curious if we may get any ORAS references/characters (aside from their Mega Evolutions). And I also mean specifically ORAS, not something which were in the original Gen III games. To list a few:
Aarune: An easily forgettable side character, if you're struggling to remember who he was Aarune was the Secret Base Expert. They expanded the Secret Base mechanic to "
Super-Secret Bases" which essentially let you turn your base into a pseudo Gym and Aarune was your tutorial and had a few side quests. You may more infamously remember him having a Flygon and
a later interview revealing it didn't get a Mega Evolution because artists couldn't agree on a good design (also to get Garchompite in ORAS you had to collect 1000 flags from other player's Secret Bases which was quite a chore).
Now you're probably thinking "
well there's no way they'll bring him back as we're stuck in Lumiose City, not that many Secret Base possibilities". But... actually I don't really have that convincing of a counter-argument without going into unsubstantiated speculation. Like the only speculation I could maybe make is there's that holographic technology thing and maybe they could use that for Secret Base making, but I'd also feel that would go against the character's "explorer" aesthetic. Unless we have some wilderness locations outside of Lumiose City, I'll admit this one is a reach... to have them finally make a Mega Flygon.
Lisia: A little more memorable, Lisia is a Coordinator Idol meant to be both the introducer and boss competitor in
Pokemon Contests Spectaculars (and she is also Wallace's niece). She's also one of the NPCs with a Signature Mega Pokemon: Altaria.
Now with them introducing a new battling system I'm not suggesting they add Pokemon Contests on top of things (THOUGH integrating Active Time Battles into Pokemon Contests like they do in the anime would be a way to spice things up). Still, Lisia being an idol and a very fashionable one at that, I could at least see her being in Lumiose City as just a tourist if nothing else. (Guess I could also give a quick mention to
Chaz, her rival who has a secret crush for her. Maybe we'll discover between the years they got together... or they can play up the joke he's a hopeless romantic but still wants to support Lisia wherever she goes (someone has to carry all her shopping bags))
Zinnia: Yeah, probably the biggest one to mention here. Zinnia may no longer be the Lorekeeper, but that doesn't mean she still can't get involved in situations concerning Dragon Legendaries. Also, I think it would be interesting if she had interactions with Emma. I always felt Emma shared some traits with Zinnia that may have meant she was a Draconid, and this would be something Zinnia may be able to recognize and give Emma a story to explore (as well as Zinnia who would in this scenario take up a mentor role).
And that's really all for the ORAS exclusive characters. Though here are some bonus Hoenn characters that got a notable expansion to their story:
Professor Cozmo: Professor Cozmo got some significant (and rather tragic) backstory expansion and had an important role in the Delta Episode. Now, you'd think Cozmo, a meteoriticist, wouldn't really have anything to do with Kalos or what's going on in Lumiose City. But there is something: Cozmo and Sycamore are friends and had worked together researching meteorites (Sycamore likely trying to find a connection between meteorites and Mega Stones). Also, let's not forget the company behind Lumiose City's redevelopment is called Quasartico Inc.; Kalos didn't really have any "space" themes but Hoenn certainly did. If there is a connection between Mega Evolution (which also means Infinity Energy) and meteorites, Professor Cozmo could be of help. Huh, as a side thought, Professor Cozmo would probably go crazy over Minior, maybe they should save him for a Sun & Moon remake or Alola Legends game.
Brigette: It's been a few gens since we moved on from Bank, would be nice to see what Brigette has been doing. Considering a part of Legends gameplay is catching (and releasing) a lot of Pokemon, and Lumiose's redevelopment plan would require someone with expertise of moving around large population of Pokemon, maybe Quasartico, Inc. could have hired her to help with the Pokemon management.
Let's see, who else can I mention... *
sees Mr. Bonding*