Buckid: I read some speculation the other day from a really hardened fan who jumped straight to the conclusion that it was
Garth of Izar, (From the third series episode "Whom Gods Destroy") but given all the superhuman jumping around in the teaser, it looks like we're back in "Augment" territory. So, maybe Khan. Or as you suggested, a mashup of the two, as Cumberbatch is wearing a Starfleet uniform every time we've seen him, but Khan should technically still be a war criminal from the 1990's at this point. (Unless continuity has been completely jettisoned.)
Continuity is unaffected.
We know from previous Star Trek time travelling that their method is the whole parallel timelines (the Borg trying to change history by assimilating Earth in the past, for example, which would rule out a single timeline as if they had been successful then they would never have needed the mission to go and assimilate Earth in the past in the first place so would never have gone, hence a paradox and so only possible with alternate parallel timelines).
In Star Trek (2009), Spock went back in time (along with those Romulan bad guys) to an alternate timeline caused by those Romulans killing Kirk's father leading to Kirk having a different upbringing and life. This did not cause a paradox so we again have alternate parallel timelines. So everything in the original Spock's life did happen, and he went to this new timeline where the events now unfold differently.
In the new timeline, Khan would be floating in space, in suspended animation in the SS Botany Bay. The original Kirk found this derelict on stardate 3141.9. However, in the new timeline who is to say that he wasn't found by some other starship captain? The changed events from the first film may have led to many changes in history, other exploring starships, different captains. Maybe in this timeline the ship that found Khan returned him to starfleet and he chose to join in order to take over from the inside and this is him now taking action to take over the Earth?