Grand Company and starting city have never been tied together, not in 1.0, and won't be in ARR. You can start in one city and join a different city's Grand Company.

However, apparently in ARR (even with already leveled 1.0 Legacy characters) our Starting City will be determined by the class we choose. And so... I'll "start" as my 50 WHM (which I would have anyway, and did in 1.0) to cement Gridania as my starting city, once again.

Also, I guess we'll also have to re-choose a Grand Company.

Quote Originally Posted by Lodestone
Version 1.0 characters will be required to progress through the main scenario quests in order to enlist in a Grand Company.

Enlisting in a Grand Company
Players will have the opportunity to choose a different Grand Company.

Ranks and Company Seals
Ranks and company seals will be restored to players upon reenlisting in their original Grand Company. Players who choose a different Grand Company will receive no such benefits.
* The ability to transfer to a different Grand Company will be implemented in an update following the start of official service.
I've already progressed through the entire main scenario... I guess they mean a new main scenario?

Either way... I'll re-enlist in the Adder! Because it's where my heart is, and also I attained max Rank and have max seals....