Honestly i dont think any rat has to be leaving in fear in this day in age, there are many examples of guys who flipped then left the program and are living out in the open and nothing happens to them. The last time i can think of the mob went after a high profile witness was when ol one eyed peter gotti was trying to take out gravano and all it got him was 25 years, and i expect the same thing to happen to anyelse planning on taking out a govt witness.