Monitors will always drive the need for faster cards.
If that's the case, then Nvidia needs to back that up with the supposed new 4k 144hz releasing end of this month. 1080Ti cannot drive that framerate.
Current cards may be selling, but there are people like me who won't upgrade to 2 year old tech out of principle, especially if they are at the same price as launch.
They simply won't get my money, and that's fine.