What limitation exists? Just the fact that right now the M1 doesn't do virtualization? At some point full x86 virtualization will need to exist on this platfor

What limitation exists? Just the fact that right now the M1 doesn't do virtualization? At some point full x86 virtualization will need to exist on this platform and when that happens you'll be able to run an x86 virtual machine on your mac to back the underlying Docker engine. This is what is happening right now with Hypervisor.framework on a Mac, for instance. If you develop a lot of ARM for sure run it all in ARM configuration but if you are a dev deploying to the current status quo you would want to continue working with x86 images if possible.