Canon have announced the current Pro 1 D X Mark III will be their last. So its likely the big manufactures will now concentrate on mirrorless.
There are still a few areas where a pro SLR is better but with cameras like the Canon R3 and Nikon Z9, the gap is now very narrow.
I can see many professionals now transitioning. Many have a high end mirrorless already, often Sony or Fuji, but with the adapters Canon and Nikon have for older glass and these new high end mirrorless cameras from the big two, many are going to transition, Canon SLR users to the Canon mirrorless R system and Nikon SLR users to the Nikon mirrorless Z system.
