One thing in the past that has, again and again, stopped me from continuing my adventure whether in Morrowind, Oblivion or Fallout 3 is Bethesda's rather ....mediocre combat system. It just feel flat and monotonous to me. There have been some mods addressing this issue but imho they failed to live up to the expectations. It is unsurprising and the creator of such mods are blameless in this, creating a new combat system is a monumental task.
Luckily, these days we have dark / demon souls combat-system which I think is really really good, at least its the best one i've tried.
How likely / feasible it is to incorporate Dark Soul -style combat into Skyrim, be it via DLC or better yet a massive mod ?