EOL means we no longer offer Support for that version. You must upgrade to 70103H08 to receive Engineering Support (bug fixes) and at least version 70103 to receive any Technical Support. Version 70103 and all the H-patches are simply bug-fixes; if you're not running the latest version of the code you will run into issues that are already fixed. There is no reason not to upgrade.
There is no situation where the firewall will stop processing all traffic in regards to licensing (unless you have never licensed the FW, of course); some features can expire (like AV) but the firewall will not suddenly stop passing traffic because that version is EOL or Support has expired.