In my personally view, they first have to feel like a FF game (which to me the last 3 haven't). So those saying a 'title', I doubt a Zelda game would feel like it when the main character isn't a guy called Link with pointy ears and a green tunic. He's a rogue biker from Detroit, called Link saving his gang with pistols from the local drug lord Ganondorf... It's called the Legend of Zelda though.
That said, to me an FF games would have these aspects, randomly occurring self contained battles using ATB with it's own unique magic/leveling system.... that's it. The main aspect that makes a game feel like other versions of it is the main focus of gameplay. This to me in FF is the battle system. Don't change it thinking that needs to improve when the reason your games are so successful is that system. Other aspects just compliment it (like a good story told during gameplay and narrative not via data sheets in the menu).
Hmm, pie.
