I received this from Silicondust by e-mail today:
Important - disable firmware auto-update on your Samsung TV today. Do not install the 1121 firmware.
Back in June we released HDHomeRun live TV and DVR support for RUI supported by Samsung 2016 series 6, series 7, and series 8 smart TVs. DVR direct on your TV without a set-top-box.
Samsung firmware update 1121 is being pushed to Samsung 2016 TVs right now. This firmware release appears to remove the RUI feature that shipped with these TVs.
Samsung TVs default to auto-updating the firmware - for the moment Silicondust recommends disabling the auto-update feature and not upgrading to 1121 until more information is available. Once updated there does not appear to be an easy way to roll back to the factory firmware.
We have reached out to Samsung for comment and will provide further updates as the situation is better understood.