They don't even need to do that... I know people like to hate on XI here, but XI is certainly a good base to work from... Why reinvent the wheel when you've got a perfectly functioning one you can improve upon? Plenty of things in XI are perfectly valid pieces of content that are certainly transferable, I mean look at our Grand Companies, then compare them to
Salaheem's Sentinels. One is a boring, characterless mini-grind with zero character, the other is at the very least a grind with characterful quests, I'd say it was pretty fun and memorable, since Assaults certainly beat the crap out of FATEs and those lame Company Levequests. Heck, forget Treasures of Aht Urghan, if Grand Companies could at least mirror vanilla Final Fantasy XIs nation missions, that would be a stark improvement over "Oh, you need a new rank? OK then, done". I'd take proper Grand Company quests, which flesh out the nations, over Hildibrand quests any day of the week... Throw meaningful content like Assault/Campaign/etc. into the mix and all the more so. Why Hamlet Defense got axed in the move from 1.0 to 2.0, I'll absolutely never understand...