They made an expansion for Oblivion devoted to the Shivering Isles so I expect they will do something similar in Skyrim. Apocrypha is imo the most interesting of the oblivion realms simply because we know so little about it.
The Enlightened, who are unable to share their boon with the world, arrive to Apocrypha. I could see it as a cheesy end-scenario for the player character.
Otherwise, a video game is unlikely to do the realm justice.
It's Hermaeus mora's realm and I liked him in oblivion he was the last daedra you can do a quest for as if you didn't know that. You had to bring him sacrifices.
I highly doubt a creature that powerful was chosen by Bethesda as the last daedric quest out of a lottery. Probably little is known about this realm because mora keeps the darker corners hidden or all to himself. If he's strong enough it would be well within his power to hide such a thing from man.