KOTOR is about upto Final Fantasies ankle.
It's inevitable there will be a third yes. But there is a big difference. Squenix loves its FF franchise , or perhaps respects would be a better word. Lucas Arts on the other hand to tend to milk, and move on when something more attractive comes up.
I can see two KOTOR scenario's. One that it's done ready for sometime next year with the same sort of layout as this one, perhaps using the droid planet.
Two, you wont see it for 2 or 3 years and when you do it will be all new and on the Xbox II.