During a fan Q&A segment at the Final Fantasy XIV Fan Festival in Paris earlier this month, FFXIV Game Director and Producer Naoki Yoshida was asked about the next game in the mainline series. While Final Fantasy XVI is hardly official yet, that hasn't stopped the fan hype train from spinning theories on what the game could be like.
Yoshida commented that he thinks the sixteenth entry in the mainline Final Fantasy series should be more straightforward fantasy and fewer mech battles:
First, if you're asking whether the Final Fantasy series will get another MMO soon, I think the chances are unlikely so long as Final Fantasy XIV is doing well. On that note, personally speaking, I'd like to see a Final Fantasy that is straightforward fantasy, one that doesn't have much machinery, and with no mecha in it. After all, we're having trouble with the Garlean Empire being too powerful. Ah, okay, that was a bad joke.
While Square Enix is still in development on the Final Fantasy VII Remake, the continued expansion plans for Final Fantasy XV were dropped late last year when director Hajime Tabata left Square Enix to start his own studio, which means development on FFXVI could begin sooner than anticipated.
So far, all of this is just speculation.