I believe Takahashi himself has said that while Xenoblade 1 was fantasy, X leans more towards sci-fi:
http://www.siliconera.com/2014/11/25/xenoblade-chronicles-x-will-deep-sci-fi-story/
"Takahashi suggested that the game would feature a 'deep' and distinctive sci-fi story compared to its predecessor's 'basic' fantasy story"







