Let me put it this way. Are DSLR's on the way out, the way digital has replaced film cameras? Do mirrorless cameras take better photos than DSLR's? I'm at a lower price range, but I would think the answers would apply to any price range.
Thats the $100,000 question. Everyone wants to know that same thing. Because everyone is asking the same question as you, I doubt you will get a straight answer from anyone. If you have nothing to loose going to mirrorless, you are in a better situation than others who have invested thousands of dollars into their DSLR's and F mount lenses asking if they should make the switch. That being said, I have both and I use both. Mainly, I use the DSLR's for fast action like sports and birds in flight and the Z6 for just about everything else. The IBIS found in the Z6 alone makes it worth it to me for that to be my daily shooter, not to mention the sharper images edge to edge using the native Z lenses and everything being lighter and more compact. The answer is not the same for any price range, unfortunately. I would not be as happy, for example with the Z50, lacking the IBIS. If you have a chance, head into BestBuy or local camera store to see if you even like the electric view finder, or if you prefer the OVF in the DSLR's. Some prefer the EVF, others hate it. I like it, but I do get the same eye fatigue after extended use that I get staring at my computer monitors too much. In my opinion, it's more about the newer technology in the sensor and processor than if the camera has a mirror or not. The mirrorless all have the newest tech. If you get a new, quality DSLR, it'd be tough to tell on a blind test what camera took what images. How ever much you want to simplify the question, it is not a simple answer.