But we KNOW that it is Mordy, and we know where it woke up, and we know that it is close to two capitals. We also know that it got a rather nice power-boost due to the Leyline.
Thus it is a rather logical step to assume that the next Dragon would be Mordremoth and subsequently also Maguuma.
Ok, just like we know Jormag is in the North, Krakawhatever is in part of Ascalon, Primordius is why the Asura moved thus he is also out there, we also have Bubbles lurking around.
Also just because the cut scene and what someone supposedly data mined does not mean it is Mordremoth, nothing says that a dragon can wake up in 1 area and stay there, it is possible they move. Also if they have Mordy in Maguuma what becomes on Primordious? From what I understand he in in the Maguuma area.
So when it comes to Anet I will not believe it is one specific dragon until it is released and regardless what it is we will not see it for quite some time. Next patch is a recap of the Scarlet line and they already said it will be a small patch. They then have the in WvWvW starting at the end of the month. After that sometime maybe in April will be the balance patch. Plus with a few games releasing expansions (WoW, Diablo) and new ones coming out (TESO) I dont see them releasing anything like a new dragon until the earliest of June or July (after the newness of the other games starts to wear off).
My guess is in the next few months they will announce an expansion (not a living story). That expansion will most likely be set to release around the 2 year anniversary. So for GW2 I believe it will be a slow summer, maybe a few small things being released. possibly starting a small living story in May or June that will lead up to the expansion.
So regardless of what dragon was shown, I do not think we will fully find out who it is for a few months.