My two cents:
They should made it as close as possible as the normal “Bethesda experience”, like Morrowind / Oblivion / Fallout 3 / Skyrim (slanted towards Skyrim especially, as it’s their latest and most successful game ever), instead of doing a WoW clone or a DAoC clone (it seems some people of that game are working in TES Online) or whatever usual MMO fare.
So like always, but allowing a few hundreds players per instance/world instead of having one player (as in the sp), and modifying a bit the design wherever it’s needed to accommodate having several players instead of one, and the world being even bigger and with more content than ever.
But I am not hopeful, it seems this is not being by proper Bethesda but by “Bethesda Online”, which really is an altogether different studio.