I doubt it would take that much time out of the schedule at all since it'll likely be in there anyway under a different guise.
I doubt it would be as simple as you're suggesting, whether or not the base functionality is there. If it's not properly designed and tested, something like this is easy to break the game -- to make it crash or be unplayable.
It's the same concept and demonstrates that it is already been tried and tested in previous games.
It's not the same concept. It's 3 major game-changing choices in the first hour or two of gameplay, and it gives you exactly one chance to change it when you complete the tutorial. It was done by necessity (which is no longer a necessity as those choices are no longer there in Skyrim).
The point is i've already done the journey it's not as fun that second time around as the sense of discovery and surprise is gone, I know how the dungeons are laid out, i know how where things/places are in the world, i know the story, i know the quests. Yeah maybe there will be a few places I didn't visit first time through or some quests i can do a bit differently but much of it will dull repetion and a waste of my time.
Luckilly Skyrim is going to help change this. With Radiant Story, quests can be modfied and tailored to your play-style, and who you know, like, and dislike. A good mage can have a different experience than an evil fighter, which can be different than a self-serving thief. Encounters you have as one character, may be skipped completely with another, or play out differently by knowing different people. Quest targets and even quest givers can change.
Plus, you'd be surprised how much of an effect changing up your play-style has on gameplay. Yeah, you may know where things are, and you may be familiar with some dungeons, but again, it's in the journey. How you get through it, what your tactics are, what you loot (different character types want/need different things), and stuff like that makes for very diferent experiences. Skyrim is taking this up a notch.