Both games were great so therefore the original teams should be involved in a Final Fantasy VI remake and new Chrono game in order for them to be great?
Did Peter Jackson need J. R. R. Tolkien in order to make The Lord of the Rings movies great? No. He just needed the books, the original source material. He couldn't use J. R. R. Tolkien's guiding hand because he's dead. Same can be said about a Final Fantasy VI remake. The original staff is not needed but the source material, the game itself, is.
The quality of the remake comes down to finding the right people for the job. That does not just mean the original team but a team that consists of capable people who are fit for the job. As Peter Jackson is a fan of The Lord of the Rings books, it'd probably help to have some guys who are fans of Final Fantasy VI working on the remake too. I mean... Who wants a bunch of people to be in charge of a remake of a mainline entry they have no interest in?
Same can be said about Chrono too. The dream team for Trigger and the original Cross team aren't needed. What is needed I think is a good development team that consists of people who have interest in the Chrono IP.