You have achievements, the scrip shop with various rewards, and the leaderboard which will open up with each new season.

Ishgard is mostly leveling content though, the whole "progress phases" thing was nothing really, you didn't miss anything. Basically the firmament zone would get a minor expansion each new milestone, and now there are quests to do in there, but that's it.

We'll see if it remains relevant with the collectable system overhaul in 5.3.