I'd like a sidequel.
Chrono Cross established that there exists 2 worlds. The home world and the another world. Chrono trigger's world was the another world in chrono cross.
So Crono, Marle, Lucca were the main characters of Chrono trigger in the another world, but what of the Crono, Marle, and Lucca of the home world? What ever happened to them? I think a game explaining that would be cool.
Also, there is no point in making another continuation of chrono series without the dream team.