Since the Abolisher is no longer functional, could Nocturnal's Skeleton Key be used to reopen the path leading to Ithelia? The lore seemingly implies this, even in ESO's Clockwork City storyline:
Now THIS is an interesting queestion. I mean Nocturnal's key can "unlock" someones potential, and Merunes' razor is implied to have been used to make Mankar camoran dragonborn.