To put it in perspective, a few years ago, I bought 50 rolls of David Romano's 2424 70mm Aerographic re-spooled into 120. I am thinking it expired in 2003, the year before he ran out and stopped doing it. Like all my 400 speed and other infrared films, it was consistently frozen at -10F or better. I still have 45 rolls of it left, shot a roll over the Summer and it is still perfect. I am thinking that based on my own personal experience, living closer to the sun than most at 8,000 feet, these films are good for at least 10 years if always kept frozen.
Stock up, this is the last of it!