According to this sneak peek
, the TV can auto-detect scope content on the fly and zoom, or ignore it, based on a user setting. So menus for scope movies are 16:9 and then the feature is zoomed to 21:9 on the fly.
They also show a 16:9 image pushed all the way to one side, accommodating a widget in the open area.
that said, it looks like at least one bit conflicts with info at vizio.com
(click the cinemawide HDTV button near the top right). The manufacturer's webiste suggests that the 21:9 TV's will also be 3D (polarized - RealD 3D) while the sneak peek link says the 21:9 is not 3D capable.
fromn vizio.com "Available later this year in 50” and 58” class sizes, these Cinemawide HDTVs also feature Razor LED™ backlighting with Smart Dimming and Theater 3D™ technology for brilliant picture quality and a superior 3D experience"