Odds of Hanging On
The bright side (for military battlefield surgeons, at least) is that there continues to be armed conflict happening all over the world. Which means there will be a continued demand for your services. In other words, being sewn back up after "absorbing" a few chunks of metal is not some fad that will go out of style in a few years. People like to be whole, so you're good there.
The other thing that'll keep you in this career is that this is the military. They don't look kindly on their doctors (or anyone, for that matter) quitting. It's called going AWOL. This means that you're kind of required to hang on.