Could be one for Z and one for something like a remake of emerald ? I dont even understand what you guys are talking about, but I think Emerald remake is going to happen...xD
I really, really doubt there will be an Emerald remake. At least not in the same generation as ORAS.
Story issues aside, and apart from the fact that ORAS could give us anything Emerald did anyway, it's simply too much work for too little gain.
There's a lot of work involved in making a Pokémon game. Scripting, coding, modelling areas/set designs, and so forth. Typically, in a generation, GameFreak has been shown to create one "pioneer game", then split it into two slightly different versions (and the split itself will happen fairly late in development. After all, all things considered, 99 % of the content is the same between versions). They will also re-create an earlier game, using much of the content and area design as the first one. While work is happening on this, another team of creators will go over the pioneer games again and add some content to make into a "third version".
This reworking of the pioneer games into a third version is more work than splitting a game into paired versions, but way less than creating an entire new region, and way, way, way less than making an entirely new game. Still, there's considerable effort and resources put into it, and it requires enough man-hours to keep the entire staff at GameFreak occupied. There wouldn't be enough staff available to rework
two regions simultaneously. The "main team" would be working on the next generation/remaking an old game (currently occupied with ORAS), while "team two" rework the pioneer games of the generation (currently occupied with "Z"). Reworking the pioneer games
and the remakes would interrupt the work schedule, and possibly the release schedule too. GameFreak and Nintendo know the projected lifetime of the 3DS, and plan their game releases accordingly. Approximate release dates for all of the Gen. VII games and spinoffs are probably planned out already.
And on the "gain" side of things, well, I doubt an Emerald remake would sell as well after ORAS, or ORAS wouldn't sell as well before an Emerald remake. It would have to have features not in ORAS to be worth a purchase, but doing so would require the designers to hold features back from ORAS - which would hurt its marketability. Stuff like the Battle Frontier is a major selling point and nostalgia element from the Hoenn games, and it would be silly of GameFreak not to include it in ORAS. Keeping it out could hurt sales, and people wouldn't be happy to have to buy more or less the exact same game later to get it.
The reason why they can do third games in the first place, is because of the novelty factor of the pioneer games. They give us an entire new generation of stuff to play with, stuff we've never seen before, and when the third game comes out, it will bring even more stuff we've never seen before. A remake, however, is basically stuff we've seen before, updated to the standards of today, with a few added bells and whistles. If ORAS held back features (the bells and whistles), it would quickly run out of selling points, especially considering that for the Emerald remake to be an Emerald remake, ORAS would miss stuff from Emerald - giving Emerald more features than ORAS, so to say. How does "hey, we remade a region you used to like, but we took away some of the most beloved features!" sound in a marketing campaign?
Keep in mind that for Pokémon, fan buzz on the Internet would make up most of the marketing. If GameFreak does a poor job with ORAS, the world will know it, and quickly, and it WILL have a major impact on sales. GameFreak need ORAS to be as good as they can, to generate sales (and money back for the resources put into development). They can afford to hold back features such as a Battle Frontier from pioneer games, because there is so much else that's new and shiny to keep the fans satisfied, but if features are missing from a remake... the fans will be rioting.
Welp, I'm rambling now. It's 1 AM here, please bear with me...
Also, look at the stuff that made Emerald a better game than Ruby/Sapphire back in the day: Animated sprites, a different story, new moves to tutor, reworked gyms, a battle frontier, more Pokémon available. Many of these things have become staples of later generations. The Pokémon roster is greatly expanded from back in the day. So are movepools. Pokémon models move now, sprites is no selling point any more. Many features that were in Emerald put not in R/S are pretty much guaranteed to be in ORAS because they have become "standard procedure" in games made since. Given that the Battle Frontier will be in ORAS (and I think it will, it's too craved for GameFreak to dare keeping it out), there wouldn't be much left for an Emerald remake to differentiate itself from ORAS. Of course, you could always add new features, but then you wouldn't have an Emerald remake any more. It would be an entirely new Hoenn game.
TL;DR: The trademark "Delta Emerald" was probably registered by GameFreak to prevent others from taking it. It's been done before.