What I would like for TES V is a sort of more “realistic” main quest. You do not have to fight gods to do something great. In this I sort of liked the “Knights of the Nine” datadisk, because you were fighting a powerful wizard, but not a god. Sure, Umaril was backed up by Meridia, but you did not fight her. Just him. I would not mind something this “simple” for TES V’s main quest. Of course what we would lack in the power of the main antagonist should be added to things like political depth of the main quest and so on, so the word “simple” refers just and only to the fact that killing a wizard (however powerful) should be easier then killing a god.
And just to clear some things up, I’m using the word “god” here to address all the god-like figures, god pretenders with god-like powers, demon lords and so on.