GNOME “Classic” will be a separate session in 3.8
It has been known that GNOME 3.8 will support a GNOME 2-ish environment through extensions. What wasn’t clear is if that option would be included in Gnome Control Center (similar to Fallback) or in Gnome Tweak Tool.
Neither will happen. GNOME “Classic” will start up a separate session, and that means we can choose it from GNOME Display Manager before we login in GNOME. In other words, gnomers will pay a lot of attention to it.