AFAIK, they essentially "just" maintained the x86 port of NeXTSTEP throughout the entire migration from NeXTSTEP to Mac OS X.
I wouldn't be amazed if they supported big-endian PPC still for the sake of maintaining portability, though I feel that's less likely than little-endian ARM.
I wouldn't be amazed if they supported big-endian PPC still for the sake of maintaining portability, though I feel that's less likely than little-endian ARM.