It's probably safe to assume 4.0 will emphasize some sort of heavier military/wartime theme, taking non-Ishgardian plot developments into consideration, prompting a justification for assigning adventurers in the Foreign Levy/Free Brigade/Yellow Serpents various positions of limited command. Would be a serious breath of fresh air, both gameplay and story-fluff wise.

There could be multiple forms of content under the overall Platoon umbrella. Nalien's Hamlet Defense / Improved Besieged idea could be one major facet of utilizing your Platoon, then have some open world content that allows you to deploy one or two Platoon members as companions to fight alongside you. If XIV tries its hand at FFXI's Campaign for whatever reason in 4.0 as an example, imagine how all of this could be utilized to further your Grand Company's standing, defending various GC-controlled outposts with other players and their own Platoons or plotting coordinated attacks on enemy strongholds.