Back in The End of Time, the time-locked Gallifrey was temporarily returned by the Master. But since the Day of the Doctor changed this into Gallifrey being
hidden in another universe, as the Time of Doctor revealed,
what will have been happening (no grammar for timey wimey, I'm afraid) to that former plot? In this new timeline the Gallifreyans don't appear to need the Master's assistance to return, but only the "Go" from the Doctor that the Universe is safe for them to return to.