If you are shipping Apps through the AppStore, they are already compatible with any hardware architecture Apple might decide to use in the future.

(You do not ship binaries to the AppStore, but LLVM-bitcode, that Apple compiles for you for whatever hardware they decide to ship next).

If you are not shipping Apps through the AppStore, you are on your own.

So shipping bytecode is not mandatory? Interesting, what % of developers are actually sending the bytecode in, then.

Shipping LLVM bitcode is mandatory for the AppStore, Apple can then compile that bitcode to binaries for different hardware.

That's why if you are shipping code to the AppStore, you probably don't really care whether Apple uses x86, ARM, RiscV, powerpc, or all of them in different devices. Producing working binaries becomes Apple's job.

Should be a lot easier this time. Most libraries that people use are already used on iOS (so already work on ARM) and there's a lot less assembly in normal software than there used to be.