I'd like either a conservative remake or a distinct sequel.
A lot of Chrono Trigger's qualities come from its graphics. And I don't just mean that the sprites are pretty, though they are. I mean that the way the sprites portray the world from a 3/4 view allow players to both easily navigate environments and determine how attacks based on positioning and proximity will work out. I suspect that a switch to 3D models, even if it looks great, could make the game play worse. HD sprites are a perfectly good alternative.
If we did get a sequel, I'd honestly not play as the old gang again. Part of me felt that Trigger closed most of its own loose ends, and even though Cross went into alternate timelines, I would prefer having a new cast if we go into a new sort of time travel or dimensional concept. Even if the game aimed for a tone and style like Trigger, I would like there to be some new ideas explored. For all the trash I've given Final Fantasy, I like how they can revisit similar ideas using a different setting and characters.
Note: I haven't ever gotten around to finding and playing a copy of Chrono Cross, partly because it didn't sound like I'd enjoy it based on what I'd heard.