@stroughtonsmith I wrote couple of apps in last 10 years for customers that use CALayer to animate features on the screen at fast pace. Currently there's no way these could be replaced with SwiftUI - and there does not seem to be a future feature on the roadmap that would do that.
This reminds me of a customer I had in the past, that used scsi protocol over USB to talk to his device - which couldn't be used anymore due to way apple treated some device drivers of the past. :/