I am not sure where you got the aluminum case for the S800. I just checked the site and the case offer is only for the Z15. Here is what it says:
"Due to Z15 few key parts delay, the shipping date of Z15 will be postponed to 2-3 weeks. Sorry for any inconvenience may be caused. Every Z15 pre-order customer will receive DJI free specific high quality aluminum case. We will shipping Z15 and DJI aluminum case out according to your payment time. We will really appreciate your patience on waiting time."
There was nothing like that on the S800 site that I could see. Maybe you have a different country specific site and could show us a link. I would like a nice case with my S800 if they are going to be available.
Boris, I think the answer to your question and others is the HDMI input may come with the launch of DJI's controller/video downlink, the Ruling. I was told that one of the S800/Z15 test videos was shot using the Ruling controller. I have to go back and look. Here is the thread, started by Kilby, where I posted everything that I know about it, which is not much.
http://www.multirotorforums.com/showthread.php?3143-DJI-Ruling
Maybe Robert and Patrick can comment more when they see it at NAB.