Microsoft owns Xbox they have to fight sony to make more money, PS3 vs Xbox.
Microsoft / Sony, are willing to pay Tons of money to win this fight by paying game studios that developing Triple A titles (Batman, CoD, GTA and yes Skyrim)
the reason Microsoft and sony are paying to delay the PC version of each game and make the game temparary exslusive for the Xbox/PS3, is that they want to prevent PC market (which is by far, the biggest of them all) of buying the game for the PC, so some crazy fan boys of certain game will buy the game for Xbox, or if needed buy AN xbox 360, just so they can play the game early, thus microsoft increases profits and xbox clients.
now im 100% sure that Microsoft will offer bethesda an "offer that they cant refuse" (here is a few millions for a month delay for the pc version), its been done alot of times before, some studios claiming that they delayed for "improving" the pc version but we all know its All about the money.
But Some powerful studios dont give up so easily for offers, the reason some wont accept microsoft or sony offer is Fans some stuidos actully care about thier fans.
so what do you think, dont say it wont happen, its just Happend to batman arkham city