Win 8 units will have Win 8 as the OS at the time of load. You will have access to Win 8 restore media via USB recovery BYOM (Bring Your Own Media) option. USB only, does not support CD/DVDs, 8GB USB recommended.
Also, in case you missed it:
For Win7 systems purchased between June 2, 2012 and January 31, 2013, the Windows 8 Promotional Upgrade program will be managed and fulfilled by Microsoft. Promotional Upgrade is available at: www.windowsupgradeoffer.com