I don’t really do much video, photo or 3d editing these days but isn’t that all GPU driven?
If that’s the case then couldn’t someone like Nvidia pick up the slack for Apple with a really nice external modular offering?
Given Apple's recent obsession with AR/VR, I wouldn't be surprised if the new apple architecture was really GPU first, CPU second. Apple has always loved graphics, and in all likelihood they recognize that a more parallel OS model might actually suit people's day to day needs better.
And even if you could most of the software in question is composed of countless components some of whom predates the mac itself and porting that to support anthing but the traditional big core CPU platform is not a trival thing to do, which is why the Xeon powered workstations and servers still exists and why manycore designs only really work in the supercomputer space.
You could argue that the workstation itself is a dead concept and that the future is "cloud" with html5 frontends even for video and CAD workloads* which is something autocad and adobe is likely working on as a long term strategy, but in the short term they need the workstation that post Jobs apple don't appear to to have any interest in building.