The notion of an old replicant seems nonsensical!

There is no logic to an aging replicant. What would be the point of some old 70s, rough voice, saggy skin, tired looking, can hardly run without panting, Deckard? It would make more sense for all replicants - be they rogue ones or Blade Runner 'cop type' replicants to look around 25 - 40. They would never succumb to old age. They would do all the jobs all the old humans couldn't do.

It's a silly concept to suggest or state Deckard is a 70 something age replicant so whatever silly storyline they've come up with let's hope they scrap the 'Deckard is actually a replicant!" bit of it!