If your character is this kind of super hero and saves skyrim from civil war and complete distruction from dragons, will you get to become king at the end?
It was annoying at the end of oblivion when you were just left as a champion, they should have at least found someone else to become heir, or said that there were no other heirs rather than just saying they will look into it. Also if you are just champion again it should mean more in the game rather than having everyone like you. it should lead to better side quests and discounts in stores and things. posible a really cool reward based on your characters stats.
What do you mean by king? DO you mean some high ruler of Skyrim? Relighting the Dragon Fire in Cyrodiil/ becoming the new emperor, and starting a new line of emperors, etc, etc... Becoming some sort of tribal war lord? WHat exactly do you mean? Because, I'm pretty sure, if you help ANYONE in the civil war, and if you DO succeed in stopping akatosh/alduin from destroying all of Nirn I still don't think that the winning side of the civil war will allow you to become ruler of Skyrim, etc...
But who knows what will happen, we haven't yet had the chance to play the game in full/ at all really, so we can not yet make a vast decision about this, and we can only really think about what may happen, and wish it to be true (but then again who knows what will happen in the full game >_>....)