I feel MGS1 would be the most likely culprit here. While it's true the other two games were PlayStation titles, I don't think either of them have the clout to be considered big titles by a non-gamer. Not to mention rumors of a MGS1 remake have been going on for years.

CC seems the least likely. I mean Xenogears has been getting some odd shout outs from SE in the last few years, but the Chrono franchise hasn't and I imagine CT would get more love before CC did if they were going to do anything with the IP.

Granted, Mitsuda does raise some eyebrows here that it could be a SE title, but the man has composed for more non-SE franchises by this point. It's not a guarantee it's one of his projects.

MGS1 to me is the only title of the three where a remake seems feasible. I feel like SE would go the remaster route first with both XG and CC before attempting a remake of either. Unless they were going for something more low grade like the Pocket editions of XV. Even then, I feel SE would play the waters safe and go remaster first.

Course it could also be for an unrelated game as well. I mean all those titles have Irish music, but it doesn't mean they couldn't just slap an Irish song onto a remake of ICO or something.