I don't know why this is even a thing. It's a remake of a 10 year old game, which has been referenced in Brawl already, and we've already seen 3rd Gen Pokemon in the Greninja trailer.
It doesn't even make sense to say it won't be referenced, because any reference to Ruby/Sapphire is the same exact thing. The only thing that won't be directly referenced is if there's anything remake-specific. We're probably not getting a Hoenn stage, but we're going to have Hoenn Pokeball/Masterball Pokemon. We've already seen Lati@s, Deoxys, Metagross, Gardevoir, etc.
There is almost nothing that would be able to be represented that wouldn't just be a reference to Ruby/Sapphire/Emerald/3rd generation in general.
So the answer is of course it will, because any ref to RSE is a reference to OR/AS. But if you mean "will it reference remake specific content?" then probably not. Not because of the release date, but because almost none of the remake specific stuff would be things that could even be referenced. It'd be stuff like a new battle frontier or new abilities/features. Things that have absolutely no way of being represented. The best you could hope for is new music.
As for not being able to reference a game that isn't out yet:
- Roy
- Metal Gear Solid 4
NONE OF US WERE CONSIDERING SCEPTILE TILL NOW
Actually, that's not true. While I, personally, never considered Sceptile, a lot of people immediately went to Sceptile as an obvious choice to 'replace' Ivysaur when we got Charizard & Greninja. All the remakes did was enforce the possibility and make people drop other possibilities.