I don't think they would nessesarily build in both processors. They'll just assume that developers will update their apps very fast. The whole XCode toolchain

I don't think they would nessesarily build in both processors. They'll just assume that developers will update their apps very fast. The whole XCode toolchain already supports x86_64 and arm64. It's trivial to build "fat" binaries with clang that run on both platforms.