This 1 of manga hit you with reality of life. The ending is very open ending (decide ur self)... I can speculated, if author itself on POV, the professor will die in middle way because, no human around him able survive, even his 'kouhai'(junior) High school... However, it NOT about ending it about the JOURNEY, that the author trying to send. Look the Professor is change through time with the robot, it very emotional...
As I said, That is Reality of Life.