I've seen estimates that you could fit Witcher 3 into Xenoblade Chronicles X three times, and Fallout 4 could fit 5 times. That FF15 map, is about 6-7ish times bigger than XBC X is, which is just about as ridiculous a map size you can have.
Video for the reference, as un-official as it is.
XBC X gets to feel pretty small though, once you have explored it all, as there are fast-travel spots all over. If FF15 doesn't have this, then the entire game is going to be just moving around, which takes the Road trip theme a bit too far, IMO.
XI Wiki





followed by "FFXV-2 Summer 2017"
