I think Square Enix will need to update regularly. This game needs more than one lv1-50 content - it needs 8. The max level isn't 50, it's 400. And this isn't even counting the crafting and gathering.

What I would like are 8 sets of lv1-50 story-lines. Perhaps doing one could unlock another? Or it's given at random for each lv1-50 until all 8 have been depleted. Perhaps there could be class-only storylines added in. Perhaps Square Enix could pull a RuneScape/The Secret World and add monthly questlines that cater to medium-level players and high-level players, each installment adding a new area or expanding on another.

What I would like is for Square Enix to add another large-scale event like the 7th Umbral Era event. Make it a long-term 5-6 month main story that gives limited-edition rewards to the players who dedicated themselves to complete it. I like being one of the heroes of old who have defeated Nael van Darnus and saved everyone from Meteor. We need more things like that so that players can explain to newbies the events that happened before they came.

Make events big so that players don't have to quest to have fun. Make a fair - decorate an entire city and have a parade like Nautilus from XIII. When the Golden Saucer comes out let them open with a bang! Grand opening party, discounts, GMs disguised as npc welcomers, receptionists, and tour guides, etc!