Chris

The game is not a spin-off, never was, never was called as such by the developers.

"It seemed as though this project was announced by Iwata as a completely new game series, so why did you retroactively make this part of the Xenoblade line?

Tetsuya Takahashi: So as it turns out, the idea of it being part of “Xeno” was always there. I have to clarify a little bit because not in the sense that it’s a sequel to the previous game but rather it is a new series that is still “Xeno”. That's how I was thinking of it."

Xeno- is not a series, it is not a metaseries despite what one moderator on wikipedia pushes, and the xeno- games do not have continuity between the various series. Xeno- just means it is a Takahashi game, with the same spirit and themes as his other xeno- games. It is a franchise, a naming convention for marketing so fans know what to expect when they buy it. They have said multiple times XCX was not connected at all to the mainline Xenoblade series. They have said Xenoblade 2 and 3 are numbered that way because XCX is not a part of the series. XCX was from its inception planned to be its own separate series. Takahashi had an entire book of lore planned for this separate series.