Not retainers, as they are not actually adventurer material (that's why they're retainers in the first place, they simply do not cut the mustard as far as adventuring is concerned, but a perfectly happy to do more 'mundane' tasks like running a bazaar at the Market), but along those lines of having actual npcs fight alongside you, then yes, definitely.

Specifically, the original version of FFXIV had the Path Companion, who would appear alongside the player during certain story quest duties (i.e. those involving the Path of the Twelve), and even had dialogue in story scenes, effectively functioning as the player's 'voice'. They even had the Echo, as they were fellow members of the Path of the Twelve, the original organization of Echo users Minfilia ran, so they even showed up in events with Primals (namely Ifrit).

Sadly there's been no mention of them returning (the chocobo companion and regular npcs fighting alongside the player in duties effectively replacing them gameplay and story wise), but expanded on they would make soloing in duties and content a lot of fun if they returned. I really hope they do - I miss my Moonkeeper kittygirl GLA Imarah.