I do agree with the basic premise proposed: The Elder Scrolls IP intrinsically makes for good MMOing.
There are some issues, though.
1 - It is a game of freedom. It actually shuns players who want a directed experience (yes, even Skyrim). Putting restrictions on top of it without a VERY good explanation will alienate fans like me.
2 - The soul of TES is the modding community. It is a Frankenstein-like relationship: Bethesda is the Doctor, since it created the body, piecing it together (haphazardly). But the electricity that moves the corpse is the modding community. It transforms the TES experience into an engrossing, creative and thorough world.
3 - They can hit the nail on the head, but they can, for the first time, actually destroy the IP. There are huge swaths of land that are yet unexplored (no, Arena and Daggerfall don't count =P). We do not have an accurate, extensive mapping of, say, Elseweyr, or Black Marsh. We know their map, cities, some PoIs, but we do not have the Morrowind/Oblivion/Skyrim treatment of them. Will these landscapes be as elaborate as their already-explored brethren? I do have some serious doubts about that.
4 - One hero, no more. Now, we'll have thousands of Nerevars and Dovahkiins (used as examples, only) roaming around Tamriel. This will strain the storytelling of a world that gravitates around the single players, single hero experience. It can be done correctly (and they started that by choosing an adequate time frame for the game, kudos for that), but it can be a big problem for the narrative.
And narrative, internal or external, is what makes TES so alluring.