I don't really know what the Supremes are going to do, and it really doesn't matter a whole bunch to me. The only effect I can see is that which ever way they decide, will bring out more political pun-dents to YAP on the TV news shows, but that is easly controled by the changing the channel.
BUT if I was to bet on their decision I'd say it will be middle of the road, Prisoners must be treated according to international treaties the US has entered into. Individual citizens that are held at Gitmo that are US citizens must recieve access to lawyers, citizens of other countries must be granted access by who ever treaties say they have the right to see. That would be my bet.