They were all on PS2, each game releasing about 2 and a half years apart, with the last game releasing about a year before the PS3's release.
With that being said, would Xenosaga, had it gained more popularity and revenue, have spread to PS4? The console was released November 15th, 2013, undoubtedly we would have had Xenosaga 4 and 5 on PS3, but would the series end on the PS4 with Xenosaga 6?
Hypothetically, let's say Xenosaga's popularity also created spin offs, like a fighting game or a entire Hakox multiplayer game, and those games were released in between Xenosaga 4 and 5, that would definitely cause Xenosaga 6 to be on PS4
Just a little something I was wondering, also something to wonder is would they keep with the inconsistent art-styles between games? With better graphics, it'd be interesting to see what they would have done.
Also, again hypothetically, would Xenosaga having enough popularity to spawn 5 sequels and ensuing spin offs over a decade of time, would it rival the big dogs like Final Fantasy?