Concept of other worlds

[StarDrake]

Yes, they've finally given us a date for the Hydaelyn/Zodiark split - it was 12,000 years ago, which would coincidentally put it around the theorized time of the end of the "Age of Gods", as Eorzeans to date have known it, and the First Umbral Era (which in most in-universe scholarship is mostly conjecture, though it's highly suspected something happened. We are evidently going to learn much more about that in Shadowbringers.

3. Our current city state looks crap in comparison to the 1st world cities. Will they revamp/remodel textures on our current ARR city states?(limsa, gridania and uldah).

This is also just a long-standing problem with games of this sort in general. The Eorzean cities were designed, depending on how you want to reckon it, either five years ago or ten years ago, and built for hardware that is now a full console generation behind us. Their designs and textures reflect the hardware limitations of the day. Kugane and the Crystarium look significantly more impressive because they were designed to make the most out of the capabilities of the PS4 and equivalent or better PC hardware.

It's possible some of these assets might spruce up the old cities, but at the end of the day, there's only so much time available to the team and it wouldn't be surprising if they focus on new content ahead of refurbishing old content.

(It's worth noting that World of Warcraft once tried to devote the vast majority of an expansion to polishing up and altering old out-of-date launch content, and the general opinion these days is that the project was a disaster that sucked down precious resources like a vortex.)