We of course cannot know the future. All we can know is the present which is currently that none of the P series monitors are given full macOS support by Dell. All you and we can do is periodically check the P3421W drivers page to see if a macOS DDPM is present.
Hi all,  I am wondering if the DDPM will be ever available for the P Series on macOS or do I really need to buy another one? I mean if this is not planned, I want to understand what the reason is.  Thank you! Sunguralp
P3421W, when will macOS DDPM be made?