Xenogears is Episode V in the original plan for the series. Since Squaresoft decided that they didn't want to do the rest of the series as planned, it was actually somewhat rewritten under the Namco brand, so it is unclear whether or not there will be a Xenosaga Episode V or if they will just go straight to VI, keeping Xenogears as Episode V. Make sense? hehehe

There is still a LOT of obvious crossover between Xenosaga and Xenogears. You can see how things are progressing through Xenosaga Episode I and II that will lead to the events in Xenogears (Episode V), but it is also obvious where they have had to change some things in order to avoid legal issues with Squaresoft. Basically, if you enjoyed Xenogears, your only shot at seeing the rest of the series is the Xenosaga series.