Man, there sure are a lot of morons on this board.
The story should not have had any alternative conclusions. The ending we got was great and any alternate endings would have taken away from the emotional weight of the story.
HOWEVER--in a game that is supposed to be about choices affecting a narrative, branching paths to the same conclusion would have improved the game significantly, and added replay value. To those who say "OMG, it's UNPOSSIBLE TO DO THIS IN A GAME, IT WOULD TAKE FOREVER TO PLOT EVERY POSSIBLE OUTCOME!!" That is a moronic argument. Even two or three divergent paths over the course of the story could have been included and would not necessarily have had to affect the ending at all. There is no reason the narrative could not have organically come back full circle to the same ending. Look at a game like Indiana Jones and the Fate of Atlantis--3 divergent paths based on a choice the player makes at a specific point earlier in the game all lead to the same final area and ending. And that was 20 years ago. It would not have been difficult to have planned this game around a few divergent narrative paths based on things like whether or not you sided with Lilly or Kenny at various points, whether you chose to go the Dairy Farm or not, who you took with you to search for Clem, etc.
Great story, but divergent paths would have been a major improvement here.