Spoiler Alert!
When Eraqus disappears, he leaves his Heart with Terra. Coming up later in the ending when MX cannot fully control Terra's body, he realizes that Eraqus' heart is with Terra, giving Terra extra strenght to fight off MX. I doubt Master Eraqus will return, but seeing as how most characters are "sleeping" in some way or form, maybe he will appear in Olympus Coliseum in Hades like Auron or he will be awakened by Sora (doubt this one because the ones he will save are the ones who called his name and others redeemable char....) but he was good to a fault. Master Eraqus will hopefully "Reconnect." in KH3.
When Eraqus disappears, he leaves his Heart with Terra. Coming up later in the ending when MX cannot fully control Terra's body, he realizes that Eraqus' heart is with Terra, giving Terra extra strenght to fight off MX. I doubt Master Eraqus will return, but seeing as how most characters are "sleeping" in some way or form, maybe he will appear in Olympus Coliseum in Hades like Auron or he will be awakened by Sora (doubt this one because the ones he will save are the ones who called his name and others redeemable char....) but he was good to a fault. Master Eraqus will hopefully "Reconnect." in KH3.