How I would have written this sequel!

Firstly, I would make the story that K has to hunt Deckard from the start. Not find him, actually be hired to kill him.

He could be assumed dead until his bones are extracted and found to be fake. The bones indicate that he is a replicant but as agent K points out “if they’re fake, how do we know for sure if he is a replicant or an actual human?”

Deckard’s status as a human or replicant is without a doubt the most talked about aspect of the first, and this will bring it back.

Agent K’s implanted memories might actually be of Deckard and he wants to know if Deckard and him had a past or if someone else’s memories exist in him (bringing in the theme of his own search of identity.)

Perhaps he keeps this hidden memory of Deckard to himself, and when tested with the eye test, he is revealed to not be loyal to the police.

His status as a loyal Blade Runner is in doubt and he is slated for termination himself, with a team of assassins after him.

His mission then is to find Deckard and learn the truth, and if Deckard is only an implanted memory, he will kill him, but if he is real, he will save him.