For Unreal and Unity-based games at least, ARM MacOS will be more or less just another compile target. For less-popular licensed engines or in-house ones, MacOS was never all that popular to begin with, so I think Apple Silicon may actually not represent that big of a change for Mac gaming.

As another comment mentions, there is the iOS to MacOS pipeline, but given that a large proportion of these are already Unity-based, the fact that MacOS now shares an architecture with iOS may prove largely incidental.