To be fair I would be amazed if anyone reading this would actually prefer any ES, especially Skyrim, to be a Multiplayer experience (which we know it won't be). I also believe that whatever effort that was put into introducing coop elements, or visiting each other's game worlds would take a lot more hassle and valuable Bethesda clicking and keying time than the benefit one would receive.
However, what would be good would be something like the Arena from OB - except you got to pick your character(s) against other people's characters from around the world.
So you would have your own personal Skyrim to gad about in, but you could go to one or two arena's scattered about the place to take other PCs on - just in the confines of that limited environment - that would be common to all player systems.
If this was to work that would have to make that area unmoddable - I don't know how many of these mods work but any mod that would give an advantage in a fight would have to be either nullified or turned off by the player before their being allowed to compete
Either random matches, matches with mates, matches against randoms in same class/type/weapon type, clan matches, game types etc
What say ye?