You also shouldn't read the comments, or basically do anything else. Focus instead on how pretty Orgrimmar looks in this picture. Final warning: spoilers after the cut.
Now, of course, this is datamining, it should definitely be taken as unconfirmed. There are other files that indicate there is something afoot, something that players might participate in, as Adriacraft posted last night in video and map format. But this might well just be a breadcrumb quest, or the opening to a cinematic, or nothing at all. It's hard to draw conclusions about what we're seeing without access to more information, but it's certainly an evocative picture, and interesting to speculate on just what might be going on here.
It looks like some Horde naval retaliation for the Alliance's attacks on Orgrimmar, and perhaps, if it's real, this is a response from Blizzard's story team to the Alliance complaints about their lack of involvement in the story this expansion. Of course, there is something of a war taking place, and it would be rather presumptuous to assume that Garrosh's reach doesn't extend to a few boats and some blue stuff. But seriously, guys, we weren't even finished fixing the Park.
And here's a video from Adriacraft!