The game can always include options for each. Not necessarily being able to become king, as I don't think that would work very well with the Elder Scrolls gameplay mechanics. I mean, would you want a king who is constantly ignoring matters of state to go off and loot dungeons? To do being a king properly, you need to allow the player to atually manage a kingdom, and really, that deserves to be its own game. Though I wouldn't mind the game giving the player the option to reach a position where you would have a degree of authority, like in Morrowind's great houses. You can join one, if you choose, and slowly rise through the ranks, though you don't get any actual management of your house's policies even once you reach the highest rank, you do get a stronghold built for you, and that's nice, I wouldn't mind seeing something like this in Skyrim, albeit with a faction more appropriate for the game. Of course, it should be an optional questline, after all, the Elder Scrolls series has always been about being who you want. Obviously, it doesn't mean you can literally be whoever you want as there must be limitations on what you can do, it's just that "Be whoever you want, within reason." doesn't sound like quite such a good slogan, still, more options never hurts, as long as it's within reason.
I've always found playing as a powerful character who's got pretty much everything he could want tends to get boring after a while. Playing as a more wandering hobo-like character with more goals to reach than there are trees in the forest is always a lot more fun and exciting.
So basically exactly what you are at the start? Generally, RPGs start with your character having nothing, but by the end of the game, your going to have come pretty far, that's the entire point, having the player start with everything would be boring because than there's nothing to strive for, but having you end with nothing would be pointless because it renders all the character progression you went through, all your struggles, utterly meaningless.