Yeah, I think the ending would have been just as good if everyone else was dead or missing, but Lee and Clementine would be walking out of Savannah into the sunset with zombies all around them. Would make a better Season 2 as well.
Just like this concept art pic:
except zombies all around, a view of Savannah and them walking towards the train. Bam, an epic ending. Take some advice, TTG.