Apple or Android, you really need a clean standalone phone with nothing on it for bitcoin, preferably will not connect to internet unless needed. So the new Android phone will still be useful for you. Now you can choose to use iPhone as an everyday phone and Android for wallet, or the other way round.
+1
Use as a real wallet. Nothing can be more unsafe than the iPhone right now, so people better not install Bitcoin wallets on them anyway. BTW, I guess soon every other app will scan for Bitcoin apps and their priv_keys, so best not to install anything on the one used for Bitcoin.