What happens when you lose your transmission while driving? I’m concerned I might, just want to know what happens and how to react.
Well if you lose it you need to pull over and go get it 
Typically, they just lose the clutches, and the transmission feels like going into neutral. On a rare occasion, a bearing can seize, and it can jam the drivetrain. These are rare, and most of the time will just drag the car to a stop. Not much you can do, but ride this one out, and try to stay in your lane. Most bearing problems will have noises before anything like this happens. I suggest you have any bearing noises checked out before they jam up on you.