In my opinion, Chrono Break would involve the breaking of a temporal causality loop. I think this is a logical progression of the time-traveling/dimension-hopping themes we have seen. Is a time-loop a good thing? If you become aware of a time-loop, would you seek to preserve it - and become immortal, or would you seek to destroy it? Who has the right to decide if a timeline created by a temporal causality loop should continue?
I think this is the best idea for a sequel, because it would create a plausible scenario in which the events of Chrono Trigger are repeated, and someone becomes aware that time is repeating. We get a new take on the consequences of space-time manipulation, and everyone gets to see their favorite characters in action one more time, as opposed to creating a completely new cast and trying to figure out how to place them into the canon.
To increase the sense of urgency, the Chrono Trigger crew will have only one chance to break the time-loop if that is what they choose to do. (Of course they would, because the original history doesn't end well for most of them.) If they cannot change things before the events of Chrono Cross play out (the direct cause of the time-loop), then time will repeat itself forever, and they will be destined to fail over and over for eternity. But if they succeed, they will have but one life to live, but they will free the future for all time. The stakes cannot get any higher than that.
