Major changes
Delaying the release to Q1 next year won't be a serious problem for most customers. RHEL 7, based on what Fedora 18 and 19 look like, will introduce significant changes in how "things get done" from an operational standpoint (for example, replacing System V inits with systemd, as well as the ability to finally do in-place major version upgrades). As a result people are going to need to take some time to adapt their existing processes and procedures to accommodate those changes.