Between this and the animal thing, I have to wonder: is this a failure of DC's editors? 'Cuz this sure seems like it. Characters like WildCat don't NEED to be taken in a new direction. They just need to be written intelligently. The JSA is full of interesting characters who are sorely underused. It seems like precious few writers can actually handle them.
There's two possibilities here: one, Mr. Terrific is dead. Two, Mr. Terrific is sorta-dead, but will be back to life in an issue or two, when the titles split (although the split will, as always, ring false...since it's manufactured justification to facilitate a marketing move: see also X-factor, Batman and the Outsiders, etc.)
Either way, a first issue where the new writer has the team defeated and/or kills off a core character to show a 'new direction' isn't shocking...it's cliche'.
C'mon Bill Willingham...I know you're capable of better than this.