:facepalm:
I take it you've never seen any other threads here about multiplayer mods?
Try searching for Oblivion Online and Oblivion Reborn to see a list of reasons why not to have or want a multiplayer mod.
Having said that, if there were an RPG with the style of a TES game that offered pseudo-co-op multiplayer, with each player making up the members of a party similar to the concept found in other single player RPGs (KOTOR, FF, etc), with p2p password protected networking, possibly only LAN, to eliminate the need for dedicated servers, and game content designed to take advantage of the multiplayer party system (coining that if it's not done already), I'd probably give it a fair go.
If you mean multiplayer in any other sense, I'd show it the door.
Fact is, that while the above idea is very, very good if I say so myself, (:P), it will probably never happen. I wouldn't put it past Beth to release a TES MMORPG, seeing as they bought Zenimax (or whatever that company is) and that type of game seems to be popular, but that's the sort of thing I wouldn't touch with a 10' barge pole.
EDIT: Also, I'm anticipating a thread lock seeing as there's only supposed to be one multiplayer discussion thread, so in the spirit of all things childish:
In b4 lok.

EDIT 2: Aformentioned thread linked to in post below mine.