Ever wanted to play Skyrim with your friend (or friends) over a local network? I sure have. But the closest thing we have available is the Skyrim Online mod, which isn't even finished yet. But I've come across something interesting: a petition for Bethesda to give us co-op DLC. I don't know if they'll listen, but I've already signed in the hopes that they will. As of this posting, the petition needs 141 more signatures before it reaches its goal of 500. Let's give them our support!
Hate to be a wet blanket, but I'm pretty sure that A) they'd never actually make something like that and B) any teams at Bethesda who worked on Skyrim have long since moved on to other projects.
I agree that a fully co-op sandbox RPG with Skyrim's scope would be pretty amazing, but I'm not sure of Bethesda is the company to bring it to us.