The body of water looks more like a murky river than an ocean and the colour schemes used in the sails and architecture seen in the background can easily be used in an Egyptian setting. Fans have also heavily demanded this setting, so all evidence, so far is pointing to an Egyptian Assassin's Creed.
The Reddit post also gives another interesting bit of information on the story of the game. Taken directly from the thread, this post reads: "one more bit of info:
game has smaller segments that take place in different times; the setting is the same though. a bit hard to exaplin without going into the story
it's not the helix rifts from acu"
So it looks like we'll finally be getting an AC game willing to tinker with the story and setting.