slightly Off topic.. But just within 2 years here we have another Fry Cry with same map different setting. Yet there are people who still believe Horizon Zero Dawn 2 will take 5 years
It's worth noting that Ubisoft is huge and has many, many teams. Most likely this game was already in development for at least a year before Far Cry 5 released.
As for Horizon 2, I am expecting it to be a PS5 title in early 2021 personally.