If you watch the original with the understanding that Deckard is a replicant then the unicorn origami and the ending have specific, complex, implications.
Now if the sequel shows Deckard as a human then they piss off everyone who prefers those implications. So, in effect, the sequel ruins the story for some people.
If the sequel shows Deckard as an aged replicant
But replicants aren't robots - they are made from the same exact biochemical structures as humans. In effect, there is not much to distinguish them from humans, from a biochemical POV, and hence, if their timespan isn't artificially limited, they can live longer than 4 years and then age, as they are made of cells in which the same processes take place as in humans.