Depends on exactly what you mean, really. Sonic X-Treme as we know it seemed like something of a mess! The game was never finished, so we have no way of knowing if it would've ended up being good... But if it came out with the level of quality that the pre-release builds we've seen imply then honestly I imagine not much about Sonic's history would've changed. Although, sometimes a game being bad doesn't matter a lot- Maybe just the concept would've sent Saturn's flying off of the shelves. There's no way to know.

If the game came out and was actually good, I doubt it would've had much impact on Sonic here in the west, for better or worse. Perhaps in Japan the Saturn having a real Sonic game like that would've kept Sonic's popularity above water over there for a while longer. As far as the games go though, Sega of Japan (back then, anyway) didn't seem very enthralled with the work SoA was doing either way, so SA1 probably would've still come out as it did and not too much would be different.