Is This The Death Star 3.0?
So, is this simply an even more dangerous Death Star that belongs to The First Order that's (finally) X-Wing proof? It's possible but not necessarily.
We do know The First Order has a super weapon in Star Wars 7 and that it's much more devastating than the Death Stars. The Official Star Wars website updated its Databank during the "Force Friday" merchandise marketing campaign and described the Starkiller Base (the base loaded with Stormtroopers seen in the trailers) with the following text:
An ice planet converted into a stronghold of the First Order and armed with a fiercely destructive new weapon capable of destroying entire star systems.
The curious wording specifies that the planet itself is a base and that the planet itself is armed. Does that mean this new solar system crushing armament is mounted to the planet and that it, itself, is the Starkiller base? You could argue that the object in the poster matches that description. Or does it mean the super weapon is a smaller craft that deploys from the Starkiller base? Could it be that it's just referring to this new Death Star that could be orbiting said ice planet?
Rumors from makingstarwars.net claim that The First Order's Starkiller ice planet base draws energy from its core and relays it to an orbiting object that can then take out a star system. Maybe that's what this is. Maybe not.
As we explained at the time of this description's reveal, a weapon that can take out solar systems is not new to Star Wars lore. In the Expanded Universe, there's a tiny, starfighter-sized craft known as Sun Crusher which could send any star into a supernova, taking out all planets in the system with it. It's possible that elements of that device have been adapted for The Force Awakens and The First Order has something like it. All we know is that The First Order has a new base of operations and that they can blow up systems.
There's another possibility though...
What If There Are Two Super Weapons?
The inclusion of another Death Star (even if it's converted planet we'll call it this) in this poster means this object is a major plot point in Star Wars 7 but this is only one movie of a story that has at least two direct sequels in the works and likely many more in the future. So, the conflict will be an ongoing one and needs to differentiate itself from what we've already seen in the films.
Some of the earliest rumors about the story and characters (a lot of which has since been proven true) revealed that Domnhall Gleeson's character (later revealed to be General Hux) was actually someone who defected from the Resistance to The First Order because the new-age rebels constructed their own super weapon. According to those reports there are some not-so-good guys in the high ranks of the Resistance so it's not a case of clear good vs. evil like there was before. Hux might be the son of someone important in the saga and he might not really be as "evil" as Gleeson described him as this summer at San Diego Comic-Con.
It's therefore possible that since The First Order's super weapon is on or attached to the Starkiller ice planet base that it has nothing to do with what's in the poster. What if the poster object is not the ice planet base and it's a new Death Star actually belonging to the Resistance? Wouldn't that be neat? That would explain its positioning in the top right of the poster, enjoying a blue-tinted light side glow alongside lightsaber-wielding Finn.