Obviously this will continue to be updated, but this is the most recent MidCity picture I've seen.
The amphitheater they used looks pretty similar to the new Ascend Amphitheater in Nashville, which would be very nice for Huntsville. Of course this picture basically shows it on the site of the movie theater, so this won't work if the movie theater is indeed staying.
EDIT: Just saw this picture which shows the movie theater north of the amphitheater.