I do not like where this is going, but I have to liken Kul'Tiras to the Ironborn from Game of Thrones.
Both are on an Island, reputed to have the best navies of their respective worlds. The Ironborn worship the so called "Drowned god" (See the similarity? N'zoth was often also presented as the "Drowned god") and their ruling house, the Greyjoys, have the Kraken for their sigil.
Now, the BFA preview showed some art of Kul'Tiras and their housing, architecture, and interiors. From the outside, the houses have taken heavily on the appearance of ships, showing just how much the Kul'Tirassians like their ships. On the inside though, a lot more sinister picture appears. (Interior of a Kul'Tirassan house, note the un-missable Kraken in the middle)
During the said preview, One of the zones - Stormsong Valley - appears to have a population of fairly devoted people. Among them, the Sea Priests, who are said to be the ones that bless each and every ship built in Kul Tiras and have dominion over the water, storms and wind. Let's take a look at one of them:
The staff is VERY similar to the Twilight's hammer symbol, with the exception that the tentacles are a bit more flow-y, and his shoulderpads are also literally Krakens. Not to mention that the "Tabard" is an Anchor literally falling into tentacles, and becomes red the lower it goes. Those priests are giving off a definite "Evil" vibe and I am almost 100% sure they will be enemies.
Now, Let's take a look at their temple' art, one of the dungeons of the zone, called Shrine of the Storm:
Very ominous indeed. All this leads me to believe that actually the Kul'Tirassians are not going to be the loyal allies that we are hoping to find on those isles, at least not to until a point where we would have to defeat N'zoth himself. The whole atmosphere of what was shown on Blizzcon just whispers "Something is wrong here" Directly into your soul.