The move to PHP 7 should not be based solely on whether XC is ready for it or not. Or if you think it gives you some advantage or not.
The main reason is PCI compliance.
If you control your server software you should move to PHP 7. Or at least start testing your cart and config to make sure all works ok and then make the move.
To me PHP 5.6.x already reached its EOL at the end of 2017.
You can continue using it until end of 2018 without breaking PCI compliance though.
http://php.net/supported-versions.php