'This town certainly has changed, and not at all for the better'

[Iscah]

I'm retracting my suggestion that it might be Nym. It's close in several ways, but it's lacking the distinct hourglass-shaped pillars that are all over both the Palace and the Floating City.

I do have a better guess that I'd dismissed too quickly at the beginning, but on a closer look I'm fairly certain of it.

I think it's Limsa.

Some of the doorways are that shape, it has similar buttresses with the curved 'cutout' section, the rounded stone pillars, and the lights seem to match. The ones either side of the door are a bit lost in the glare, but the other two look right: the wall-mounted lantern and the two-part hanging light with a globe and a smaller cylinder under it.

Checking back against the trailer, if it is Limsa, then I think the first shot of them running up the staircase is inside the lighthouse.

[CaesarCV]

Honestly I'm still of the opinion that it is, simply enough, supposed to resemble/be Ul'Dah. It's a location immediately connected to Thancred (the Ul'Dah scion in 1.0 and early 2.0) and it kind of looks like it. I'm not expecting complete accuracy in cinematic trailers, since, well, they are a different artstyle than the game. That being said, they have purposely misled with trailers before (albeit moreso in patch than cinematic trailers) so we can't really be sure.