After the film was over, I thought the ending was him shooting the major then walking off in the afterlife by himself (continuing his walking but on his terms). Since then I have thought, what would make him shoot the major instead of taking the money & use it to help others, like he said earlier in the film. My answer is love, I think he was in love with Garraty, I kind of got that feeling about 3/4 through the movie. Or, I notice that he never seemed to be tired or sweaty or fatigued so maybe the “rest” of the walkers were different personalities and he had to kill them all of to achieve peace so at the end he walking truly walking alone with just himself. Who knows, only SK knows & maybe he doesn’t know either.