What does this mean for Astrophotography?

Good news. Likely not much. While the two CPUs are not compatible from a software standpoint, Apple is providing an emulation layer that will keep compatibility on both platforms.

Intel based Macs will work long into the future. Apple is providing the ability to compile “Fat binaries” meaning, that each application will have the correct components to run on both Intel and Arm based Macs. Existing software will continue to work.

If you purchase one of the ARM based Macs at the end of the year when released. An emulation layer will allow existing Intel based applications to run on the new chips. During their developer preview of the technology, they showed high end 3D applications running full speed on an ARM based Mac. So it seems like there will not be issues with emulation.

An additional bonus, because the ARM based Macs use the same CPUs that are in the iPhone and iPad, Mac desktops will be able to run all iOS applications natively, and Apple intends to makes these available on the Mac App Store. So all your favorite iPhone and iPad astronomy apps will now be on your desktop.