If you think about it, limit breaks are highly special damaging or supportive spells. and each character has them, Light has Army of Hua, Vanille has Death, etc.... these are for the one characters only and simply can be used anytime, i think these replaced Limits.
The paradigm shifting takes precedence over earning a limit since the shifting is required in many battles to get a high rating, so i think they simply made "limits" a anytime cast.
The closest thing to limit breaks in this game is the stagger system. Unfortunately, staggering is nowhere near is fun as limit breaks were.
I think 'Overclock' mode was originally the limit break system for the game but they took it out. It would have been nice to have another way to break up the monotony of most of the boss battles but oh well.I believe monotony is what they were aiming for in this game. This is why they took out towns, not any of this 'PS3 can't handle towns' garbage.