Ishgard starting city?

The fact that there are three new Jobs introduced and none of them require a prerequisite class raises one question: Do you think Ishgard will become a new starting city?

The problem I see with this is that a Levels 1-15 storyline involving Ishgard wouldn't really fit in with the Main Scenario after the merge, as Heavenward technically happened well after the current Level 50 content.

As far as the lore behind the Jobs goes, I believe it's more likely that they'll work in a similar fashion to the "advanced" Jobs from XI - that is, you won't be able to start off as one and instead will need to have at least one Disciple of War/Magic up to Level 30 in order to "unlock" whatever quest gives you the appropriate Soul Crystal - only instead of using mostly abilities from the base classes, they will be their own classes that have to be leveled from 1 after unlocking.

Astrologian sounds like it may be Ishgard's equivalent of Conjurers/Thaumaturges (judging by the fact that the current Coerthas zones have some astrology towers), but the other two seem more ambigous - a lot of people have thrown out theories about the Machinist and Dark Knight storylines involving Admiral Merlweb & General Raubahn respectively. My guess is the new Jobs probably won't have official Guilds like the base classes, but rather they will be similar to Ninja in that they all have their own reasons for being in Heavensward, and by extension, will each have a relevant storyline to go with them.

Plus, if the new Jobs did start out of Ishgard, I think SE would have confirmed this in the announcement.

It was discussed already; Ishgard won't be a starting city (and there won't be housing there for now) simply due to the fact that the war with dragons isn't making that place exactly safe. Making it a starting city would also conflict with the 2.0 storyline where Ishgard isn't even mentioned to new players at the start. There's also the fact that the expansion is supposed to have monsters beyond level 50, so do you really want a new player to be starting out in a place where they will get mauled?

I think it will be a bit like Jeuno in FF11, it will be the biggest hub, but not the starting city