It's been implied;
http://forum.square-enix.com/ffxiv/t...st-(2016-04-12)
Seems like a "Please look forward to it!" kinda deal, whether that sits in the same pile as FC Primal Summoning or not though... I believe the initial concept came up as "Crystal Tower is dead, what if you had a group of NPCs to get you through it?", then it was "You can take them in dungeons maybe", and now it's devolved to Garrisons...
I'd hope squads are just going to be built upon over time... SE really needs to put Hamlet Defense back in the game... These squads could have some amazing synergy with Hamlet Defense... You send them off to do stuff in the preparation phase, and that impacts the enemy strength, defense strength, NPC levels, etc., during the actual fight... Heck, if they keep Hamlet Defense as an instance instead of going full Besieged, they can even have the parties squad actually show up in the battle...