The plot involving K trying to find out if he's real or not is intriguing but in hindsight I don't think it's strong enough material to sustain a 2 hours 45 mins movie and undermines the central concept of Blade Runner. The original Blade Runner was about cops of the future killing artificial humans. The replicants are the villains. However, in Blade Runner 2049 there's hardly any chasing of any replicants. K does retire a replicant in the opening act but after that there is no sense of K needing to retire any other replicants.

What if Wallace had sent replicants out to kill K and Deckard.... and Deckard is not captured. He agrees to help K. Deckard returns as a Blade Runner - gun in hand! Deckard would use his past Blade Runner skills to help K track down Wallace's replicants. You could still have the subplot involving Rachael's child but you'd frame that subplot within a larger storyline involving K and Deckard actively trying to find and retire Wallace's elite unit of replicants. Suggested in hindsight, this would be make for a stronger sequel? I reckon so.