IOT management no problem
@Richard12 others have said this is about apps working in an ipv6 only environment. So possible no change to ipv4 environments.
But let's assume your mobile operator moves to ipv6 only on compatible iOS devices. Does this break access to ipv4 iot? I say no. So the iOS network will contain NAT64/DNS64 to connect to legacy ipv4 domains. If you are managing devices using URLS in DNS, no problem, automatically translated by DNS64. If you are connecting to IPv4 addresses direct in the iOS devices browser then apple are allegedly bringing you a bump-in-the-stack to synthesise an ipv6 NAT64 destination to pass you via NAT64. Will NAT64 connect you OK? Yes, if it works via NAT44 today it can work via NAT64. If you need a public address today and a NAT free path, then you will have issues, until v6 end to end. But if that was the case we would have all moved to v6 years ago.