Really all that Xenoblade Chronicles X needs to be consistent with Xenogears are two name changes and a date change.
New Jerusalem = New Los Angeles
M24 = Mira
500 years to prepare the exodus from earth = 50 years.

There might be more, I can’t think of any though. There could be a Zohar in Xenoblade Chronicles X that hasn’t entered the plot yet.

The story fits very nicely in the slot of the foundation of New Jerusalem, since New LA at the end of Xenoblade Chronicles X seems very well situated to being the founding city and future capital of a Galactic Empire (assuming they can reopen passage. The imminent threat is gone for a time. But there are other possibilities to consider: Retelling the Xenogears story without the Galactic Empire with the White Whale being Eldridge.

1. Mira is cut off.
2. Most human bodies would be synthetic creations of the Kadamony device
3. While we don’t have an Abel shown, it doesn’t necessarily mean he is absent.

The big missing factor would be the Deus weapon. Takahashi would need to write something new into that slot to be the purpose for a higher dimensional being somehow living on Mira. It might be that the Zohar exists for some non-human project on Mira, maybe a Samar thing - I don’t want to speculate too much, because there’s literally a ton of possibilities. So, a sequel would:

A. Involve the establishment of a Galactic Federation in the near future (a few years to a few hundred years later) or:
B. Take place on Mira thousands of years down the road ina Xenogears-like retelling.

Something that hints toward ‘Option A’ is Xenoblade Chronicles 2 - the multiple Titans are like multiple planets orbiting a central area... it was likely a lot safer to go that direction than planets to get a feel for multiple smaller worlds and how he can keep them toned down in size without it feeling too limited.

If Takahashi is still reading Asimov, particularly the Foundation sequels (or the Robot/Elijah Trilogy) then there’s some very interesting stories to tell. Although Xenosaga was already heavily influenced by Asimov - particularly Foundation.

I describe myself as a little dose of toxic masculinity.