For ranged you could maybe move from Formations to combo synergy. While still close together myabe a cap on how many can be bunched (unless thats a handy way for the devs to write an attack that hits all your mages at once)

Maybe a CNJ's Aero and a THM's Fire on "formation" combo makes a firestorm. Possible effects could include hitting more targets, longer burning with higher damage (since your fanning the flames so to speak)

Since Ranged biggest boon is distance and mobility may have a stronger case for having their "formations" more of a synergy of spellcasting then base placement vs the enemy.

Another idea for casters/ranged in formation could be Maybe an Arher infront of a BLM. when the archer uses say, heavy shot. It gains an elemental dmg, or direct path damage, (aka it hits the target and any enemies more or less directly between the archer and the target.

That could make for some skillful positioning party wide for the tanks to line up multiple enemies, and the archer to target the farthest away. thus hitting all of them.

But the possabilities are really endless.