I'm sure if someone had put Windows xp in the DVI monitor in 2002 it would not be usable right now.
Lots of ATMs still run Windows XP Embedded today, for better or worse.
An operating program like iOS is a complex system of a bunch of programs that have their vulnerabilities and they depend on each other. Over time, this will become increasingly difficult to keep in stable operation.
Yes, but those vulnerabilities are largely irrelevant in a device that's basically airgapped.