Why even think about violating this franchise the way TESO has done to TES? TESO barely has any players on it anymore. Even though Zenimax keeps churning out new content for it.
Let's face it, single player franchises like TES and Fallout are phenomenal for the simple reason they allow the player to
1. be innovative with sandbox game play
2. have access to unlimited gaming immersion and new content (from mods, character builds, and game world exploration opportunities)
3. have unlimited access to high resolution, unique weapons, clothing, building, crafting customization of their PCs AND the gaming environment. Heck you can even add a stomach/bowels and give your PC a real reason to eat food in the vanilla game. Or give your PC and/or other NPCs sixual needs, realistic nvde textures, diseases, health monitoring/healing systems etc. etc. All of these are possible in TES games like Skyrim. And in FO3 and NV.
NONE of this degree of customization is remotely possible in online game play like TESO. Online game play removes the gamer's ability to customize their game world to their specifications. With an online game, you're no longer playing your game, but the dev's game. Or likely a hacker/modder/cheater's game with the epic fail that GTAO has devolved to.
So none of 1-3 would work in a MMO/PvP style game. You'd have to give up customization and sandbox immersion for functionality and performance. And game lag. TESO is the perfect example of how uninspiring online game play can pervert a franchise into.