It's my opinion that the TFA trailer gives away a lot more information than one might initially think. Based on what is seen in the teaser(s), it's obvious that JJ intends for TFA to have the same look and feel of the original trilogy. That said, lets examine what we know about the "First Order." The scene in teaser 2 where we see what appears to be a First Order rally is very reminiscent of Nazi Germany, the template used for the empire in the original trilogy. The First Order stays true to that template, making use of blacks, reds, and whites etc. so on and so forth. With that, we can assume that the lineage of the First Order is rooted within the former Galactic Empire in someway. The Galactic Empire appears to have fallen in some way sometime after the events of ROtJ, but the question that is begs to be asked is in what capacity was it dissolved? Is the First Order a remnant or off shoot of the empire led by former imperial officers turned warlords, each vying for power after the emperor's demise? Or is the First Order the result of competing rebel factions after their initial victory over the empire? Keep in mind that the Rebel Alliance, like the Galactic Empire, appears to no longer be a major player in galactic events; what we are left with is the "Resistance." I'm more inclined to think that the First Order is an offshoot of both the empire and the rebellion, but more the rebellion. After all, putting a war torn galaxy back together is no easy task. Perhaps the rebellion was not prepared for the overwhelming responsibility of rebuilding the galaxy. Like I said before, Star Wars has always drawn on historical events to help shape it's narrative. For example, the Treaty of Versailles was an attempt, however poor, to rebuild a war torn Europe after WWI. Those who crafted the treaty became victims of their own vanity. They all but failed to stabilize the post war world, thus allowing for the rise of Hitler and the Nazis. Could we be seeing a similar situation unfolding in TFA? Who knows, it's all speculation, but I think it could be an interesting take on why the Rebel Alliance and Galactic Empire appear to no longer exist. Furthermore, such an explanation could pit our heroes against one another, an interesting dichotomy indeed.