Earlier quoted context omitted.
I think you should stick to Apple, frankly. Every time Apple comes up with something new (or just a new software release), people come out of their sheds to warn about all the bad things that will happen. And then almost none of those bad things happen. I've witnessed this dozens of times now, so a safe interpretation would be to assume that this time none of those things happen.
Not running 32bit code anymore die definitely happen
Do you want to be burdened with layers of backwards compatibility and end up like POSIX or Autoconf with provisions for things that once run on some long forgotten UNIX OS version?