SHOW IS CANCELLED, THERE WON'T BE A SEASON 3
So here's the deal, I just read this and I wanted to share with people since I enjoyed this show: Netflix owns the IP for Kingdom, and in SK they tend to sell different productions around IPs they own like web novel adaptation, musicals, theatre, you name it they do it, only so they can actually make money out of the IP. Netflix - and this came straight from the creators - denied their request to have the IP expand within SK market, maybe even international market considering how successful and popular this series was, so they weren't making money out of Kingdom, so why would the creators keep focusing on an IP that isn't worth the hassle since Netflix can flat out stop them from making money?
That is how the series was "cancelled" without being cancelled, Netflix has 0 interest in cancelling the show because it is popular and they make money from it, but the creators don't have interest because they can't expand their adaptations and actually make money out of it, so Netflix washes their hands, you won't see any news like "Netflix cancels popular series" because by contract they place the whole responsibility on the creators. Such a shame because it was a very unique IP.