I think it would be cool if there a new gallifrey came into existence since Gallifrey was ruined. Put your ideas here if you want.
Here is my idea/story:
Say there was another "Gallifrey" on the other side of the Gallifreyan sun, like Mondas/Telos and Earth. The inhabitants of this world developed time travel before gallifrey did. They saw what happened to Mondas, and what happened to Gallifrey in the time war. Therefore they removed thier entire planet from space to avoid destruction.
Since they were apart from the universe, there was nothing to age them, except for the occasional time wind. They took space ships from other planets and converted them into undercover time ships. They created a defence system and specialized weapons. They took Daleks, Cybermen and any other race which is part of the Alliance. They converted them to do good and gave some emotions back. They did all this to prepare for the eventual return into the universe.
When Gallifrey was destroyed, they decided it was time to go take its place. The only thing left was to get a real Timelord and his TARDIS.
(to be continued)