Several possibilities with promo materials:
-MS probably hasn't released a final logo for the new Xbox to anyone yet (if it even exists yet), so it couldn't be put on promo material.
-It's possible that Bungie is going to announce their game prior to MS announcing their new box, so obviously they couldn't mention that it is coming to the new Xbox at that time.
-That promo material could very well not be final, as it hasn't been released intentionally yet.
I'm going to go ahead and make the assumption that Destiny is a more expensive than Halo 4 considering it will have at least 2 versions (possibly 4 with possible ports to PC and the new Xbox) and Bungie is a larger studio than 343. Activision wants this to be the biggest game in the world for the next 10 years, and the plan has been laid for games and expansions for that time period, I seriously doubt they didn't throw some pretty insane money at this.
Why wouldn't you assume that Bungie would release for the ps4 then as well? Seeing as how they have been rumored to launch pretty close to one another and the fact that more and more leaks about orbis have come rather than durango.
Activision is smart, and while they may want Destiny to become a huge success it isn't guaranteed. I don't think Activision gave them close to the money Microsoft allowed 343 for Halo 4. Not even Treyarch got that much for Black Ops 2. You give that much money for a well established game/name, not for one that may or may not sell. I love Bungie, they're perhaps my favorite studio, that doesn't mean I don't have a knot in my stomach that Destiny may not be as good as I hope.
Is Bungie truly larger? The article from digital foundry showed that 343 called on Microsoft dx11 engineers and artists, other studios etc. I remember Kiki saying in an interview at one point they had 500+ employees working at 343 on Halo 4. In the recent article with Polygon, it's stated Bungie has about 350 in crunch. Naturally these numbers go down once the main game ships. 343 is definitely leaner now, but it's now an independent studio, backed by a publisher which had whispers of being for sale.
Activision may want Destiny to carry its name forward, but a modern warfare 4 or Black Ops 3 or whatever they have planned for next gen launch is going to dominate sales. As much as I hate the series now, I won't deny it has a name recognition and sales that are unmatched. I have 40 year old uncles who buy call of duty and 6 year old cousins who buy call of duty.
I'll admit they don't have the logo finalized and that's why the promotional pieces didn't have any mention of next gen, I'm just saying when you have GTA 5 only being current gen, you have games like watch dogs be current gen, why do you think bungie, which is going multi platform for the first time in a long time internally, can support not only millions of ps3 users, but now add a new console as well? I just don't see it. I hope I'm wrong and we have a better version for the nextbox but I have a feeling it's Xbox 360/PS3 launch and maybe pc port later.
Let's remember one final thing, Activision is only a publisher. It's not like 343/MS or Bioware/EA, bungie is its own company, and Activision has to run its own studios and has shareholders to answer to, they won't write a blank check for Bungie.