I don't believe that torpedos disappear when the vehicle that dropped them dies.
Last night or the night before I took off from a CV to find a PT boat about 2k out in front of the cv group. I immediately killed it. The guy driving it was Lynx. A short time later (less than a minute) the cruiser died. Then the CV died. The guy had unloaded his torpedos, and because of my ground detail settings I hadn't seen any wakes, so hadn't turned the CV group. His torpedos had clearly survived his PT boat's death.
I've had torpedos kill ships after my TBM died many times in the past, but this thing with Lynx was since the latest update, so it's still that way.