If the way the storyline or game play seems odd to some and great to others,and the ending etc is not to everyones taste,then the most logical thing to do is to just write a side quest as long as the main quest that changes and advances the timeline like a movie,then as time passes the player could be involved in helping to build a totally new world civilization,while fighting those that were hindering it.
Also other parts of the glode could be used with new landmasses etc with new NPC`s and world cities,the game does not have end as long as modders and scripters keep it going.
The choises are endless.