I don't think they need to go any further with Xenogears.
Any attempts to further that story are one way tickets to a 1,000,000 mph fall from grace with a resounding (ass splattering) crunch.
they can either remake it, reboot it or relaunch it.
its kind kind of hard to move past such a climactic theme based ending which includes the denial of living in an eternity of peace for the short deep existential love between two people....
I like the game, I like the story, I'm okay with the philsophy but I've been working on a concept that trumps it.