Honestly, I think people are reading into the trailer a bit too much. The Heavensward trailer did three things:

1. It told us it would be set in Ishgard.
2. It told us that Dragoons would be the focal job of the expansion.
3. It got us hyped to fight some f*cking dragons.

If you look at the Stormblood trailer (which is actually a trailer of the trailer), it does pretty much the exact same thing:

1. It tells us it will be set in Ala Mhigo.
2. It tells us Monk will be the focal job of the expansion.
3. It gets us hyped to anime fight some f*cking Garleans.