Normal Mages are learning time travel magic, and regular Bronze Dragons like Chromie can use it; it's not a special Aspect only ability. There's nothing to suggest Nozdormu has lost his ability to wield that magic either.
In End Time, we kill Murozond, but in that version of the future, Deathwing wasn't killed in the Maelstrom, so in our timeline that fight against Murozond never comes to pass and he's not killed.