When Riku confronted the new organization Young Xehanort said that the most future Xehanort would soon appear refering to a limp shadowy figure that I assumed was the recreating Terra-Xehanort. But then after the fight with Young Xehanort the old man Master Xehanort was there. And the last time we saw that incarnation he faded away and disappeared because his heart was now inside Terra. I'm guessing that Master Xehanort's original body must've been recovered and had part of Xehanort's heart placed back into it. And maybe that process is what I thought was the recreating of Terranort but with the twists and turns this story keeps taking, I'm probably wrong. If anyone has any other theories or information I'm not aware of I'd love to hear them.