eh, I wouldn't doubt it. There have been rumors flying around about a potential 003 for awhile...but they dwindled down after M-Audio released the Project Mix.
Although, why the would include it with 7.3 if they didn't want people speculations, I don't know. They could have just as easily released the DLL file with the new hardware.
Assuming this file does have something to do with a future hardware upgrade....could be just a simple file for PT itself (although do you notice a 002 or mbox.dll file? Not sure why they would need one unless it's something new).