Many of the future customers who will be using the FF35 sensor (either on the Epic or Scarlet) will use spherical lenses that cover the full sensor (such as still lenses) BUT will later crop to widescreen (16:9 or 1.85). This will be for reframing in post purposes: very akin to shooting Academy 35mm with the aim of finishing 1.85 for theatrical distribution. Since reframing is a hugely valuable extra tool to have in post, I am absolutely positive that some - if not many - users will go this route if they have the right lenses (despite the added bandwidth and storage necessary for this etc).
In this respect, I think an extremely helpful feature on the FF35 cameras will be the ability of the viewfinder and the LCD monitor (and other monitoring devices) to display a 16:9 (or 1.85) center extraction of the 3:2 sensor image, despite the camera shooting full sensor. Especially since most monitoring devices are 16:9. Of course, the user will have the ability to monitor the entire 3:2 image (it will probably have black bars left and right on the widescreen LCD) if he so wishes - but since the top and bottom of the picture will be cut anyway, this approach makes a lot of sense.
You shoot for 16:9, you monitor 16:9 - knowing all the time that you are recording a lot of extra picture on top and at the bottom of what you're seeing, which you can use later in post anytime you need to reframe.
I think it makes a lot of sense. What do you think?